Host cities:
| Athlete | Nation(s) | Sport(s) | Role(s) | Era | Notes | 
|---|---|---|---|---|---|
| Blaž Medvešek |  SLO | SWM | Olympics | 2000—2004 | 1–0–0 2005 İzmir SWI gold: 200 m backstroke | 
| Michael Meeks |  CAN | BKB | Olympics | 2000 | 0–1–0 1993 Buffalo BAS silver | 
| Folkert Meeuw |  FRG | SWM | Olympics / Non-starter | 1968—1976 | 0–1–1 1973 Moskva SWI silver: 200 m Butterfly, 4×100 m medley relay | 
| Helge Meeuw |  GER | SWM | Olympics | 2004—2012 | 2–1–0 2007 Bangkok SWI gold: 50 m backstroke and 100 m backstroke; 2009 Beograd SWI silver: 100 m backstroke | 
| Gheorghe Megelea |  ROU | ATH | Olympics | 1976 | 1–0–0 1975 Roma ATH gold: javelin throw | 
| Ferdinando Meglio |  ITA | FEN | Olympics | 1980—1992 | 1–1–2 1981 București FEN gold: sabre team; 1983 Edmonton FEN silver: sabre team; 1987 Zagreb FEN bronze: sabre and sabre team | 
| Jemal Megrelishvili |  GEO  URS | WRE | Olympics | 1972 | 1–0–0 1973 Moskva WRE gold: Greco-Roman featherweight -62 kg | 
| Məmmədəli Mehdiyev |  AZE | JUD | Olympics | 2016—2020 | 0–0–1 2013 Kazan JUD bronze: half-middleweight -81 kg | 
| Annika Mehlhorn |  GER | SWM | Olympics | 2004 | 1–0–0 2009 Beograd SWI gold: 200 m butterfly | 
| Krzysztof Mehlich |  POL | ATH | Olympics | 1996 | 0–0–1 1995 Fukuoka ATH bronze: 110 m hurdles | 
| Stefano Mei |  ITA | ATH | Olympics | 1984—1988 | 2–0–0 1985 Kobe ATH gold: 5000 m; 1989 Duisburg ATH gold: 5000 m | 
| Petra Meier-Felke |  GDR  GER | ATH | Olympics | 1988—1992 | 1–0–0 1981 București ATH gold: javelin throw (competed as Petra Felke for East Germany) | 
| Kersten Meier |  FRG | SWM | Olympics | 1972 | 0–0–1 1973 Moskva SWI bronze: 4×100 m medley relay | 
| Maaris Meier |  EST | CRD | Olympics | 2004 | 0–1–0 2011 Shenzhen CYC silver: mountain biking | 
| Heike Meißner |  GER | ATH | Olympics | 1992—2000 | 2–0–0 1993 Buffalo ATH gold: 400 m hurdles; 1995 Fukuoka ATH gold: 400 m hurdles | 
| Doris Meister |  FRG | SWM | Olympics | 1968 | 0–0–2 1973 Moskva SWI bronze: 4×100 m freestyle relay and 4×100 m medley relay | 
| Amadou Méité |  CIV | ATH | Olympics | 1972—1976 | 0–1–0 1979 Ciudad de México ATH silver: 4×100 m relay | 
| Amel Mekić |  BIH | JUD | Olympics / Other | 2004—2012 | 0–0–1 2003 Daegu JUD bronze: half-heavyweight -100 kg | 
| Viktor Melantyev |  ROC  RUS | CSP | Olympics | 2008—2020 | 3–0–0 2013 Kazan CAN gold: C2 200 m, C2 500 m, and C2 1000 m | 
| Yevgeny Meleshchenko |  KAZ | ATH | Olympics | 2004—2008 | 0–1–0 2001 Beijing ATH silver: 400 m hurdles | 
| Lori Melien |  CAN | SWM | Olympics | 1988 | 0–1–0 1993 Buffalo SWI silver: 4×100 m freestyle relay | 
| Luis Felipe Méliz |  CUB  ESP | ATH | Olympics | 2000—2012 | 0–1–0 1999 Palma de Mallorca ATH silver: long jump (competed for Cuba) | 
| Faina Melnik |  ARM  URS | ATH | Olympics | 1972—1980 | 1–0–1 1973 Moskva ATH gold: discus throw, bronze: shot put | 
| Boris Melnikov |  RUS  URS | FEN | Olympics | 1964 | 0–1–1 1963 Porto Alegre FEN silver: sabre team, bronze: sabre | 
| Nikolay Melnikov |  RUS  URS | WPO | Olympics | 1972—1976 | 2–0–0 1970 Torino WAP gold; 1973 Moskva WAP gold | 
| Hanna Melnychenko-Kasianova |  UKR | ATH | Olympics | 2008—2016 | 0–0–1 2007 Bangkok ATH bronze: heptathlon | 
| Tetiana Melnyk |  UKR | ATH | Olympics | 2016—2020 | 1–0–0 2019 Napoli ATH gold: 4×400 m relay | 
| Refik Memišević |  SRB  YUG | WRE | Olympics | 1980—1984 | 0–1–0 1981 București WRE silver: Greco-Roman super-heavyweight +100 kg | 
| Jesús Mena |  MEX | DIV | Olympics / Other | 1988—1992 | 0–1–0 1991 Sheffield DIV silver: platform | 
| Kata Menczinger |  HUN | WPO | Olympics | 2012 | 0–2–0 2009 Beograd WAP silver; 2017 Taipei WAP silver | 
| Tamás Mendelényi |  HUN | FEN | Olympics | 1960 | 2–0–0 1959 Torino FEN gold: sabre team; 1961 Sofia FEN gold: sabre team | 
| Carolina Mendoza |  MEX | DIV | Olympics | 2012—2020 | 1–1–1 2019 Napoli DIV gold: synchronized springboard, silver: team, bronze: mixed synchronized springboard | 
| Nurlan Mendygaliyev |  KAZ  URS | WPO | Olympics | 1988 | 1–0–0 1985 Kobe WAP gold | 
| Ana Menéndez |  ESP | ATH | Olympics | 1996 | 0–0–1 1999 Palma de Mallorca ATH bronze: 1500 m | 
| Osleidys Menéndez |  CUB | ATH | Olympics / Other | 2000—2008 | 1–0–0 2001 Beijing ATH gold: javelin throw | 
| Ronald Menezes |  BRA | SWM | Olympics | 1984 | 0–0–1 1981 București SWI bronze: 4×100 m freestyle relay | 
| Sérgio de Menezes |  BRA | ATH | Olympics | 1988—1992 | 0–1–0 1989 Duisburg ATH silver: 400 m | 
| Meng Jie |  CHN | FEN | Olympics | 2000—2004 | 2–1–0 2001 Beijing FEN gold: foil team, silver: foil; 2003 Daegu FEN gold: foil team | 
| Meng Kebate'er |  CHN | BKB | Olympics | 1996—2004 | 0–1–0 2001 Beijing BAS silver | 
| Argentina Menis |  ROU | ATH | Olympics | 1972—1976 | 0–2–0 1973 Moskva ATH silver: discus throw; 1975 Roma ATH silver: discus throw | 
| Carol Menken-Schaudt |  USA | BKB | Olympics | 1984 | 1–1–0 1981 București BAS silver (competed as Carol Menken); 1983 Edmonton BAS gold | 
| Aleksandr Menkov |  RUS | ATH | Olympics | 2012 | 0–1–0 2013 Kazan ATH silver: long jump | 
| Pietro Mennea |  ITA | ATH | Olympics / Other | 1972—1988 | 5–0–2 1973 Moskva ATH gold: 200 m, bronze: 100 m and 4×100 m relay; 1975 Roma ATH gold: 100 m and 200 m; 1979 Ciudad de México ATH gold: 200 m and 4×100 m relay | 
| Emanuele Merisi |  ITA | SWM | Olympics | 1992—2004 | 1–2–1 1993 Buffalo SWI silver: 200 m backstroke, bronze: 100 m backstroke; 1997 Catania SWI gold: 200 m backstroke, silver: 4×100 m medley relay | 
| Reinhard Merkel |  FRG | SWM | Olympics | 1968 | 0–0–1 1970 Torino SWI bronze: 400 m medley | 
| Aleksandra Merkulova |  RUS | GRY | YOG | 2010 | 1–2–0 2013 Kazan RGY gold: ball, silver: all-around and ribbon | 
| Iryna Merleni-Mykulchyn |  UKR | WRE | Olympics | 2004—2012 | 1–0–0 2005 İzmir WRE gold: freestyle featherweight -51 kg (competed as Iryna Merleni) | 
| Ken Merten |  USA | SWM | Olympics | 1968 | 3–0–0 1967 Tokyo SWI gold: 100 m breaststroke, 200 m breaststroke, and 4×100 m medley relay | 
| Leila Meskhi |  GEO  URS  EUN | TEN | Olympics | 1988—1992 | 2–1–0 1987 Zagreb TEN gold: singles and doubles, silver: mixed doubles | 
| Romain Mesnil |  FRA | ATH | Olympics | 2000—2012 | 0–0–1 1999 Palma de Mallorca ATH bronze: pole vault | 
| Mónica Messa |  ESP | BKB | Olympics | 1992 | 0–1–0 1991 Sheffield BAS silver | 
| Dayaris Mestre |  CUB | JUD | Olympics | 2012—2016 | 0–0–1 2013 Kazan JUD bronze: extra-lightweight -48 kg | 
| Miklós Meszéna |  HUN | FEN | Olympics | 1964—1968 | 4–0–0 1961 Sofia FEN gold: sabre team; 1963 Porto Alegre FEN gold: sabre team; 1965 Budapest FEN gold: sabre and sabre team | 
| Adrian Metcalfe |  GBR | ATH | Olympics | 1964 | 2–0–0 1963 Porto Alegre ATH gold: 400 m and 4×400 m relay | 
| Linda Metheny |  USA | GAR | Olympics | 1964—1972 | 0–2–0 1967 Tokyo GYM silver: all-around and team | 
| Gert Metz |  FRG | ATH | Olympics | 1968 | 1–0–0 1965 Budapest ATH gold: 4×100 m relay | 
| Darren Mew |  GBR | SWM | Olympics | 2000—2004 | 0–0–1 2007 Bangkok SWI bronze: 50 m breaststroke | 
| Gabrielle Meyer |  FRA | ATH | Olympics | 1968 | 2–1–0 1967 Tokyo ATH gold: 200 m and 4×100 m relay, silver: 100 m | 
| Ann Meyers |  USA | BKB | Olympics | 1976 | 0–1–0 1977 Sofia BAS silver | 
| Ulrike Meyfarth |  FRG | ATH | Olympics / Other | 1972—1984 | 0–1–0 1979 Ciudad de México ATH silver: high jump | 
| Anne Meygret |  FRA | FEN | Olympics | 1984 | 0–0–1 1983 Edmonton FEN bronze: foil team | 
| Ruslan Mezentsev |  UKR | GAR | Olympics | 2000—2004 | 0–1–0 2003 Daegu GYM silver: team | 
| Miao Bo |  CHN | BKB | Olympics | 1996 | 0–1–0 2001 Beijing BAS silver | 
| Miao Lijie |  CHN | BKB | Olympics | 2004—2012 | 1–1–0 2001 Beijing BAS silver; 2003 Daegu BAS gold | 
| Giovanni Miccoli |  ITA | ROW | Olympics | 1988 | 0–1–0 1987 Zagreb ROW silver: coxed fours | 
| Łukasz Michalski |  POL | ATH | Olympics | 2012 | 1–0–0 2011 Shenzhen ATH gold: pole vault | 
| Angelina Michshuk |  KAZ | SHO | Olympics | 2012 | 0–0–2 2013 Kazan SHO bronze: skeet team; 2015 Gwangju SHO bronze: skeet team | 
| Igors Miglinieks |  LAT  URS  EUN | BKB | Olympics | 1988—1992 | 0–1–0 1989 Duisburg BAS silver (competed for the Soviet Union) | 
| Ambra Migliori |  ITA | SWM | Olympics | 2004 | 0–0–1 2009 Beograd SWI bronze: 4×200 m freestyle relay | 
| Aurélio Miguel |  BRA | JUD | Olympics / Other | 1988—1996 | 0–1–1 1985 Kobe JUD silver: half-heavyweight -95 kg, bronze: open class | 
| Yelena Migunova |  RUS | ATH | Olympics | 2008 | 2–1–0 2005 İzmir ATH gold: 4×400 m relay; 2011 Shenzhen ATH gold: 4×400 m relay, silver: 400 m | 
| Bogdan Mihăilescu |  ROU | WPO | Olympics | 1972 | 0–0–1 1965 Budapest WAP bronze | 
| László Mihályfi |  HUN | ATH | Olympics | 1964 | 2–1–1 1961 Sofia ATH gold: 200 m, bronze: 100 m; 1963 Porto Alegre ATH gold: 4×100 m relay; 1965 Budapest ATH silver: 4×400 m relay | 
| Miloš Mijalković |  SRB  SCG | JUD | Olympics | 2004 | 0–0–1 2001 Beijing JUD bronze: half-lightweight -66 kg (competed for FR Yugoslavia) | 
| Damir Mikec |  SRB | SHO | Olympics | 2008—2020 | 0–1–0 2011 Shenzhen SHO silver: 50 m free pistol | 
| Dmytro Mikhai |  UKR | ROW | Olympics | 2012—2016 | 0–2–0 2013 Kazan ROW silver: eights; 2015 Gwangju ROW silver: eights | 
| Viktor Mikhalchuk |  URS  UKR | VVO | Olympics | 1968 | 1–1–0 1965 Budapest VOL gold; 1970 Torino VOL silver | 
| Aleksandr Mikhaylin |  RUS | JUD | Olympics | 2012 | 0–1–0 2001 Beijing JUD silver: heavyweight +100 kg | 
| Anatoly Mikhaylov |  RUS  URS | ATH | Olympics | 1956—1964 | 2–0–0 1961 Sofia ATH gold: 4×100 m relay; 1963 Porto Alegre ATH gold: 110 m hurdles | 
| Vladimir Mikheyev |  RUS  URS | SWM | Olympics | 1976 | 0–3–0 1977 Sofia SWI silver: 400 m freestyle and 4×200 m freestyle relay; 1979 Ciudad de México SWI silver: 400 m medley | 
| Andrei Mikhnievich |  BLR | ATH | Olympics | 2000—2012 | 1–0–0 2003 Daegu ATH gold: shot put | 
| Esko Mikkola |  FIN | ATH | Olympics | 2004 | 0–1–0 2003 Daegu ATH silver: javelin throw | 
| Paolo Milanoli |  ITA | FEN | Olympics | 2000 | 0–1–1 1993 Buffalo FEN bronze: épée team; 1995 Fukuoka FEN silver: épée | 
| Philip Milanov |  BEL | ATH | Olympics | 2016 | 1–0–0 2015 Gwangju ATH gold: discus throw | 
| Igor Milanović |  SRB  SCG  YUG | WPO | Olympics / Other | 1984—1996 | 0–0–2 1987 Zagreb WAP bronze; 2011 Shenzhen WAP bronze | 
| Joel Milburn |  AUS | ATH | Olympics | 2008 | 0–1–0 2007 Bangkok ATH silver: 4×400 m relay | 
| Jearl Miles-Clark |  USA | ATH | Olympics | 1992—2004 | 1–1–0 1989 Duisburg ATH gold: 4×400 m relay, silver: 400 m (competed as Jearl Miles) | 
| Kostiantyn Miliaiev |  UKR | DIV | Olympics | 2008 | 1–1–0 2009 Beograd DIV gold: platform; 2011 Shenzhen DIV silver: team | 
| Mitar Milinković |  IOA  SRB  SCG | JUD | Olympics | 1992—1996 | 0–1–0 1995 Fukuoka JUD silver: heavyweight +95 kg (competed for FR Yugoslavia) | 
| Alina Militaru |  ROU | ATH | Olympics | 2004 | 0–1–0 2003 Daegu ATH silver: long jump | 
| Billy Miller |  AUS | WPO | Olympics | 2012 | 1–0–0 2009 Beograd WAP gold | 
| Coby Miller |  USA | ATH | Olympics | 2000—2004 | 2–0–0 1999 Palma de Mallorca ATH gold: 200 m and 4×100 m relay | 
| Cody Miller |  USA | SWM | Olympics | 2016 | 0–0–1 2013 Kazan SWI bronze: 4×100 m medley relay (swam in heats only) | 
| Craig Miller |  AUS | WPO | Olympics | 2000—2004 | 0–0–2 1995 Fukuoka WAP bronze; 1997 Catania WAP bronze | 
| Inger Miller |  USA | ATH | Olympics | 1996 | 1–0–0 1995 Fukuoka ATH gold: 4×100 m relay | 
| Shannon Miller |  USA | GAR | Olympics | 1992—1996 | 1–1–0 1997 Catania GYM gold: all-around, silver: team | 
| Alice Mills |  AUS | SWM | Olympics | 2004—2008 | 1–0–4 2007 Bangkok SWI bronze: 100 m freestyle and 50 m breaststroke; 2011 Shenzhen SWI gold: 4×100 m freestyle relay, bronze: 50 m butterfly and 100 m butterfly | 
| Noam Mills |  ISR | FEN | Olympics | 2008 | 0–1–0 2007 Bangkok FEN silver: épée | 
| Bojana Milošević |  SRB  YUG | BKB | Olympics | 1988 | 1–0–1 1985 Kobe BAS bronze; 1987 Zagreb BAS gold | 
| DeLisha Milton-Jones |  USA | BKB | Olympics | 2000—2008 | 1–0–0 1997 Catania BAS gold | 
| Saša Mimić |  YUG | ROW | Olympics | 1980 | 0–0–1 1987 Zagreb ROW bronze: eights | 
| Florin Mina |  ROU | VVO | Non-starter | 1980 | 1–0–0 1981 București VOL gold | 
| Katsuyuki Minami |  JPN | VVO | Olympics | 1992 | 1–0–0 1993 Buffalo VOL gold | 
| Gor Minasyan |  ARM | WLF | Olympics / YOG | 2010—2016 | 1–0–0 2017 Taipei WLT gold: super-heavyweight -105 kg | 
| Ildikó Mincza-Nébald |  HUN | FEN | Olympics | 1992—2008 | 3–1–1 1993 Buffalo FEN gold: foil (competed as Ildikó Mincza); 1995 Fukuoka FEN silver: foil (competed as Ildikó Mincza); 1997 Catania FEN gold: foil team and épée team, bronze: foil (competed as Ildikó Mincza) | 
| Sergey Mindirgasov |  RUS  URS | FEN | Olympics | 1988 | 3–0–0 1983 Edmonton FEN gold: sabre team; 1985 Kobe FEN gold: sabre and sabre team | 
| Gianni Minervini |  ITA | SWM | Olympics | 1984—1992 | 0–1–0 1985 Kobe SWI silver: 100 m breaststroke | 
| Viktor Minibayev |  ROC  RUS | DIV | Olympics | 2012—2020 | 1–4–2 2011 Shenzhen DIV silver: platform and synchronized platform, bronze: team; 2013 Kazan DIV silver: synchronized platform and team, bronze: platform; 2017 Taipei DIV gold: team | 
| Dominick Minicucci, Jr. |  USA | GAR | Olympics | 1988—1992 | 0–0–1 1991 Sheffield GYM bronze: pommelled horse | 
| Irina Minkh |  RUS  URS  EUN | BKB | Olympics | 1988—1992 | 1–0–0 1985 Kobe BAS gold | 
| Yu Minobe |  JPN | GAR | Olympics | 2008—2012 | 4–2–0 2011 Shenzhen GYM gold: uneven bars, balance beam, and team; 2013 Kazan GYM silver: team; 2015 Gwangju GYM gold: balance beam, silver: team | 
| Ildar Minshin |  RUS | ATH | Olympics | 2008 | 0–0–1 2011 Shenzhen ATH bronze: 3000 m steeplechase | 
| Sašo Mirjanič |  SLO  YUG | ROW | Olympics | 1988—1992 | 0–0–1 1987 Zagreb ROW bronze: eights (competed for Yugoslavia) | 
| Victor Mirshawka |  BRA | BKB | Olympics | 1964 | 1–0–0 1963 Porto Alegre BAS gold | 
| Alfio Misaggi |  ITA | WPO | Olympics | 1980—1988 | 1–0–0 1987 Zagreb WAP gold | 
| Valentina Mishak |  URS  UKR | VVO | Olympics | 1964 | 3–0–0 1961 Sofia VOL gold (competed as Valentyna Voloshchuk); 1965 Budapest VOL gold; 1970 Torino VOL gold | 
| Hanna Mishchenko |  UKR | ATH | Olympics | 2008—2012 | 1–0–0 2011 Shenzhen ATH gold: 1500 m | 
| Saša Mišić |  MNE | WPO | Olympics | 2016 | 0–0–1 2011 Shenzhen WAP bronze | 
| Arsens Miskarovs |  LAT  URS | SWM | Olympics | 1980 | 2–0–1 1981 București SWI gold: 200 m breaststroke and 4×100 m medley relay, bronze: 100 m breaststroke | 
| Michele Mitchell |  USA | DIV | Olympics | 1984—1988 | 0–1–0 1985 Kobe DIV silver: platform | 
| Morgan Mitchell |  AUS | ATH | Olympics | 2016—2020 | 0–0–1 2019 Napoli ATH bronze: 4×400 m relay | 
| Victoria Mitchell |  AUS | ATH | Olympics | 2008—2016 | 0–1–0 2005 İzmir ATH silver: 3000 m steeplechase | 
| Silviya Miteva |  BUL | GRY | Olympics | 2012 | 0–0–1 2013 Kazan RGY bronze: ribbon | 
| Branislav Mitrović |  SRB | WPO | Olympics | 2016—2020 | 1–0–1 2009 Beograd WAP bronze; 2011 Shenzhen WAP gold | 
| Aki Mitsuhashi |  JPN | HOC | Olympics | 2012—2020 | 0–0–1 2013 Kazan HOK bronze | 
| Eizaburo Mitsuhashi |  JPN | VVO | Olympics | 1984—1988 | 0–0–2 1979 Ciudad de México VOL bronze; 1981 București VOL bronze | 
| Risako Mitsui |  JPN | SWA | Olympics | 2012—2016 | 0–3–0 2013 Kazan SYN silver: duet, team, and team Free Routine Combination | 
| Takashi Mitsukuri |  JPN | GAR | Olympics | 1960—1964 | 1–0–0 1961 Sofia GYM gold: all-around | 
| Yasuaki Mitsumori |  JPN | VVO | Olympics | 1968 | 1–0–0 1967 Tokyo VOL gold | 
| Yuko Mitsuya |  JPN | VVO | Olympics | 1984 | 0–1–0 1991 Ciudad de México VOL silver | 
| Hanako Miura |  JPN | GAR | Olympics | 1992—1996 | 0–0–1 1993 Buffalo GYM bronze: team | 
| Nobuyoshi Miura |  JPN | ATH | Olympics | 1968 | 0–0–1 1967 Tokyo ATH bronze: 3000 m steeplechase | 
| Rina Miura |  JPN | GRY | Non-starter | 2012 | 0–3–1 2013 Kazan RGY silver: group 10 clubs and group 3 balls + 2 ribbons, bronze: group all-around; 2015 Gwangju RGY silver: group 6 clubs + 2 hoops | 
| Junichi Miyashita |  JPN | SWM | Olympics | 2008 | 0–0–1 2005 İzmir SWI bronze: 100 m backstroke | 
| Takiri Miyazaki |  JPN | DIV | Olympics | 2004 | 0–0–1 2001 Beijing DIV bronze: synchronized platform | 
| Koichi Mizushima |  JPN | GAR | Olympics | 1988 | 0–0–1 1987 Zagreb GYM bronze: team | 
| Jun Mizutani |  JPN | TTE | Olympics | 2008—2020 | 0–0–1 2009 Beograd TTN bronze: team | 
| Hisashi Mizutori |  JPN | GAR | Olympics | 2004 | 3–2–0 2001 Beijing GYM silver: team; 2007 Bangkok GYM gold: all-around, horizontal bar, and team, silver: floor | 
| Gülcan Mıngır |  TUR | ATH | Olympics | 2012 | 0–0–1 2013 Kazan ATH bronze: 3000 m steeplechase | 
| Mo Ke |  CHN | BKB | Olympics | 2004 | 0–1–0 2001 Beijing BAS silver | 
| Sławomir Mocek |  POL | FEN | Olympics | 2000—2008 | 0–1–1 1999 Palma de Mallorca FEN silver: foil team, bronze: foil | 
| Sachi Mochida |  JPN | SWM | Olympics | 2016 | 0–1–1 2019 Napoli SWI silver: 4×100 m freestyle relay, bronze: 200 m butterfly | 
| Vincenzo Modica |  ITA | ATH | Olympics | 2000 | 0–0–1 1993 Buffalo ATH bronze: 10000 m | 
| John Moffet |  USA | SWM | Olympics | 1984 | 3–0–0 1985 Kobe SWI gold: 100 m breaststroke, 200 m breaststroke, and 4×100 m medley relay | 
| Ehsan Mohajer Shojaei |  IRI | ATH | Olympics | 2008 | 1–0–0 2007 Bangkok ATH gold: 800 m | 
| Aida Mohamed |  HUN | FEN | Olympics / Other | 1996—2020 | 1–1–0 1997 Catania FEN gold: foil team; 1999 Palma de Mallorca FEN silver: foil | 
| Tino Mohaupt |  GER | SHO | Olympics | 2008—2012 | 2–0–1 2007 Bangkok SHO gold: 10 m air rifle and 50 m rifle prone team, bronze: 10 m air rifle team | 
| Ihor Mohylnyi |  UKR  EUN | ROW | Olympics | 1992—1996 | 1–0–0 1993 Buffalo ROW gold: quadruple sculls (competed for Ukraine) | 
| Mok Un-Ju |  PRK | GAR | Olympics | 2000 | 0–0–1 2001 Beijing GYM bronze: team | 
| Stephen Mokoka |  RSA | ATH | Olympics | 2012—2020 | 2–2–1 2007 Bangkok ATH bronze: 10000 m; 2011 Shenzhen ATH silver: 10000 m; 2013 Kazan ATH gold: 10000 m and half marathon team, silver: half marathon | 
| Ilya Mokretsov |  KAZ | FEN | Olympics | 2016 | 1–0–0 2005 İzmir FEN gold: sabre team (competed for Russia) | 
| Markéta Mokrošová |  CZE | BKB | Olympics | 2008 | 0–0–1 2001 Beijing BAS bronze | 
| Maksim Mokrousov |  RUS | BOB | Olympics | 2014 | 1–0–0 2009 Beograd ATH gold: 4×100 m relay | 
| Yury Molchan |  RUS | FEN | Olympics | 2004 | 0–0–3 2003 Daegu FEN bronze: foil team; 2005 İzmir FEN bronze: foil and foil team | 
| Marcela Moldovan-Zsak |  ROU | FEN | Olympics | 1976—1984 | 1–2–0 1977 Sofia FEN silver: foil team (competed as Marcela Moldovan); 1981 București FEN gold: foil team (competed as Marcela Moldovan); 1983 Edmonton FEN silver: foil team (competed as Marcela Zsak) | 
| Nikolina Moldovan |  SRB | CSP | Olympics | 2012—2016 | 0–1–2 2013 Kazan CAN silver: K2 200 m, bronze: K1 200 m and K2 500 m | 
| Olivera Moldovan |  SRB | CSP | Olympics | 2012—2016 | 0–1–1 2013 Kazan CAN silver: K2 200 m, bronze: K2 500 m | 
| Valter Molea |  ITA | ROW | Olympics | 1988—2000 | 1–0–0 1987 Zagreb ROW gold: eights | 
| Carlo Molfetta |  ITA | TKW | Olympics | 2004—2012 | 1–0–0 2003 Daegu TKW gold: lightweight -72 kg | 
| Fabíola Molina |  BRA | SWM | Olympics | 2000—2012 | 0–1–0 1997 Catania SWI silver: 100 m backstroke | 
| Juan Manuel Molina |  ESP | ATH | Olympics | 2004—2008 | 1–1–0 2001 Beijing ATH silver: 20 km walk; 2005 İzmir ATH gold: 20 km walk | 
| Lyuba Mollova |  BUL | ATH | Olympics | 1972 | 0–0–1 1973 Moskva ATH bronze: javelin throw | 
| Endre Molnár |  HUN | WPO | Olympics | 1968—1980 | 0–0–1 1970 Torino WAP bronze | 
| Gyula Molnár |  HUN | WRE | Olympics | 1980 | 0–1–0 1973 Moskva WRE silver: Greco-Roman bantamweight -57 kg | 
| István Molnár |  HUN | VVO | Olympics | 1964 | 0–1–0 1965 Budapest VOL silver | 
| Tamás Molnár |  HUN | WPO | Olympics | 2000—2008 | 0–1–0 1995 Fukuoka WAP silver | 
| José Luis Moltó |  ESP | VVO | Olympics | 2000 | 0–1–0 1995 Fukuoka VOL silver | 
| Anne-Sophie Mondière |  FRA | JUD | Olympics | 2008—2012 | 1–0–1 1999 Palma de Mallorca JUD gold: team; 2001 Beijing JUD bronze: open class | 
| Dan Money |  GBR | BOB | Olympics | 2010 | 0–0–1 1997 Catania ATH bronze: 4×100 m relay | 
| Aurore Mongel |  FRA | SWM | Olympics | 2004—2008 | 1–0–0 2003 Daegu SWI gold: 4×100 m freestyle relay | 
| Mönkhbaataryn Bundmaa |  MGL | JUD | Olympics | 2008—2012 | 1–0–0 2007 Bangkok JUD gold: half-lightweight -52 kg | 
| Mönkhbatyn Urantsetseg |  MGL | JUD | Olympics | 2012—2020 | 0–1–1 2009 Beograd JUD silver: extra-lightweight -48 kg; 2015 Gwangju JUD bronze: extra-lightweight -48 kg | 
| Jérémy Monnier |  FRA | SHO | Olympics | 2012—2016 | 0–1–0 2011 Shenzhen SHO silver: 50 m rifle three positions team | 
| Yasunori Mononobe |  JPN | SWM | Olympics | 2008 | 1–0–0 2009 Beograd SWI gold: 4×200 m freestyle relay | 
| Attila Monostori |  HUN | WPO | Olympics | 1996 | 0–1–0 1997 Catania WAP silver | 
| Niurka Montalvo |  CUB  ESP | ATH | Olympics | 1996—2004 | 1–0–0 1993 Buffalo ATH gold: triple jump (competed for Cuba) | 
| Carlo Montano |  ITA | FEN | Olympics | 1972—1976 | 0–1–1 1977 Sofia FEN bronze: foil team; 1979 Ciudad de México FEN silver: foil team | 
| Mario Aldo Montano |  ITA | FEN | Olympics | 1972—1980 | 0–0–1 1970 Torino FEN bronze: sabre team | 
| Mario Tullio Montano |  ITA | FEN | Olympics / Referee | 1972—1988 | 1–0–2 1967 Tokyo FEN gold: sabre team, bronze: sabre; 1970 Torino FEN bronze: sabre team | 
| Noelle Montcalm |  CAN | ATH | Olympics | 2016—2020 | 0–1–0 2013 Kazan ATH silver: 4×400 m relay | 
| Manuèla Montebrun |  FRA | ATH | Olympics | 2000—2008 | 1–0–1 1999 Palma de Mallorca ATH bronze: hammer throw; 2001 Beijing ATH gold: hammer throw | 
| Pablo Montes |  CUB | ATH | Olympics / Non-starter | 1968—1976 | 0–1–0 1970 Torino ATH silver: 4×100 m relay | 
| Anne Montminy |  CAN | DIV | Olympics | 1992—2000 | 1–1–1 1993 Buffalo DIV gold: platform, silver: team; 1999 Palma de Mallorca DIV bronze: platform | 
| Roberto Monzón |  CUB | WRE | Olympics | 2004—2008 | 0–0–1 2005 İzmir WRE bronze: Greco-Roman lightweight -60 kg | 
| Hannah Moore |  USA | SWM | YOG | 2014 | 0–0–1 2017 Taipei SWI bronze: 1500 m freestyle | 
| Kendis Moore |  USA | SWM | Olympics | 1968 | 2–0–0 1967 Tokyo SWI gold: 100 m backstroke and 4×100 m medley relay | 
| Maya Moore |  USA | BKB | Olympics | 2012—2016 | 1–0–0 2009 Beograd BAS gold | 
| Jeroen Mooren |  NED | JUD | Olympics | 2012—2016 | 1–0–0 2009 Beograd JUD gold: extra-lightweight -60 kg | 
| Sajjad Moradi |  IRI | ATH | Olympics | 2004—2012 | 1–0–0 2009 Beograd ATH gold: 800 m | 
| Salvatore Morale |  ITA | ATH | Olympics / Non-starter | 1960—1972 | 2–0–1 1959 Torino ATH gold: 400 m hurdles; 1961 Sofia ATH gold: 400 m hurdles; 1963 Porto Alegre ATH bronze: 400 m hurdles | 
| Juan Morales |  CUB | ATH | Olympics | 1968—1972 | 0–1–0 1970 Torino ATH silver: 4×100 m relay | 
| Matteo Morandi |  ITA | GAR | Olympics | 2004—2012 | 0–0–1 2005 İzmir GYM bronze: rings | 
| Martina Moravčíková |  CZE | SWM | Olympics | 2012—2016 | 0–0–1 2015 Gwangju SWI bronze: 200 m breaststroke | 
| Martina Moravcová |  CZE  TCH  SVK | SWM | Olympics | 1992—2008 | 5–0–1 1995 Fukuoka SWI gold: 100 m freestyle, bronze: 200 m medley (competed for Slovakia); 1997 Catania SWI gold: 100 m freestyle, 200 m freestyle, 100 m butterfly, and 200 m medley (competed for Slovakia) | 
| Roman Moravec |  TCH  SVK | ATH | Olympics | 1972 | 0–0–1 1973 Moskva ATH bronze: high jump | 
| Abderrahmane Morceli |  ALG | ATH | Olympics | 1980—1984 | 0–0–1 1977 Sofia ATH bronze: 1500 m | 
| Sara Moreira |  POR | ATH | Olympics | 2008—2020 | 2–1–0 2009 Beograd ATH gold: 5000 m and 3000 m steeplechase; 2011 Shenzhen ATH silver: 5000 m | 
| Yipsi Moreno |  CUB | ATH | Olympics | 2000—2012 | 0–1–0 2001 Beijing ATH silver: hammer throw | 
| María Moret |  CUB | BKB | Olympics | 1980 | 0–1–0 1979 Ciudad de México BAS silver | 
| Keith Morgan |  CAN | JUD | Olympics | 1996—2008 | 1–0–0 1999 Palma de Mallorca JUD gold: middleweight -90 kg |