Namesakes
Belgian Prime Ministers:
1 prime minister
Leo Tindemans 1974-1978 
Bishops of Rome and the Popes:
13 popes
Leo I the Great 440-461
Leo II 682-683
Leo III 795-816
Leo IV 847-855
Leo V 903
Leo VI 928
Leo VII 936-939
Leo VIII 964-965
Leo IX 1049-1054
Leo X 1513-1521
Leo XI 1605
Leo XII 1823-1829
Leo XIII 1878-1903
Characters in Greek Mythology:
1 character
Leo (m)
Fictional Characters from Television:
5 characters, 1 hero
Leo Dalton 1996 Silent Witness
Leo Chingkwake 1998 That '70s Show
Leo Markus 1998 Will & Grace
Leo Wyatt 1998 Charmed
Leo Fisher 1999 Once and Again
Leo Mason 2012 Major Crimes
German Chancellors and Presidents:
1 chancellor
(chancellor) Leo von Caprivi 1890-1894
Hall-of-Famers:
2 baseball, 1 football, 1 ice hockey
(baseball) Gabby Hartnett (middle name Leo) 1955
(football) Leo Nomellini 1969
(ice hockey) Leo Boivin 1986
(baseball) Leo Durocher 1994
Irish Presidents and Prime Ministers:
1 prime minister
(prime minister) Leo Varadkar 2017-2020; 2022-2024
Most Valuable Players:
1 winner
Gabby Hartnett (middle name Leo) 1935 baseball
Nobel Prize Winners:
1 physics
(physics) Reona Esaki (a.k.a. Leo) 1973
Notable Actors and Entertainers:
8 actors
Leo Carrillo 1880-1961
Leo G. Carroll 1886-1972
Leo Genn 1905-1978
Lee J. Cobb (a.k.a. Leo) 1911-1976
Leo McKern 1920-2002
Branscombe Richmond (middle name Leo) 1955-
Taye Diggs (middle name Leo) 1971-
Leo Howard 1997-
Notable Athletes:
1 ice hockey, 1 soccer
(ice hockey) Leo Boivin 1931-2021
(soccer) Leo Canjels 1933-2010
Notable Businesspeople:
1 businessperson
Leo Fender 1909-1991
Notable Filmmakers:
2 directors
Leo McCarey 1898-1969
Joseph L. Mankiewicz (middle name Leo) 1909-1993
Notable Musicians:
2 singers, 1 composer, 1 musician
Léo Delibes 1836-1891
Johnny Hallyday (middle name Léo) 1943-2017
Leo Sayer 1948-
Norman "Fatboy Slim" Cook (middle name Leo) 1963-
Notable Scientists and Inventors:
1 inventor, 1 physicist
Leo Fender 1909-1991
Reona Esaki (a.k.a. Leo) 1925-
Notable Writers:
1 author
Leo Tolstoy 1828-1910
Olympic Medalists:
5 bronze, 3 silver, 2 gold/bronze, 1 gold, 1 silver/bronze
(gold/bronze) Leo Goodwin 1904; 1908 diving - plunge for distance; swimming - 4x50 yard freestyle relay; water polo; swimming - 4x200 m freestyle relay
(bronze) Leo Larrivee 1924 3000 m team
(gold) Leo Sexton 1932 shot put
(bronze) James Dillion (middle name Leo) 1952 discus throw
(bronze) Veikko Karvonen (middle name Leo) 1956 marathon
(bronze) Leonhard Pohl (a.k.a. Leo) 1956 4x100 m relay
(silver) Benny Nielsen (middle name Leo) 1988 swimming - 200 m butterfly
(silver) Leo Peelen 1988 cycling - track
(silver/bronze) Leo Visser 1988; 1992 speed skating
(gold/bronze) Leonardo Gutiérrez (a.k.a. Leo) 2004; 2008 basketball
(silver) Leonel Manzano (a.k.a. Leo) 2012 1500 m
(bronze) Leo Komarov 2014 ice hockey
Oscar Award Winners:
2 directors
(director) Leo McCarey 1938; 1945 The Awful Truth; Going My Way
(director) Joseph L. Mankiewicz (middle name Leo) 1950; 1951 A Letter to Three Wives; All About Eve
Other Leaders:
1 president
President Leo Falcam 1999-2003 Federated States of Micronesia
Roman and Byzantine Emperors:
7 emperors
Emperor Flavius Valerius Leo (a.k.a. Leo) 457-474
Emperor Flavius Leo Junior (a.k.a. Leo) 474
Emperor Leo 695-698
Emperor Leo 717-741
Emperor Leo 775-780
Emperor Leo 813-820
Emperor Leo 886-912
Saints:
17 saints, 5 blessed
Saint Leo ?-260
Saint Leo the Great c. 400-461
Saint Leo ?-541
Saint Leo ?-550
Saint Leo II 611-683
Saint Leo III 750-816
Saint Leo ?-787
Saint Leo IV 790-855
Saint Leo of Carentan 856-890
Saint Leo Luke ?-900
Saint Leo ?-900
Saint Leo of Nonantula ?-1000
Saint Leo IX 1002-1054
Saint Leo of Lucca ?-1079
Blessed Leo of Saint-Bertin ?-1163
Saint Leo Karasuma ?-1597
Saint Leo Tanaka ?-1617
Blessed Leo Nakanishi ?-1619
Saint Leo Satsuma ?-1622
Blessed Leo Suchiemon ?-1622
Blessed Leo Kombiogi ?-1628
Blessed Leo Ignatius Mangin ?-1900