- Apr 1 Beau Jack, American boxer (NYSAC world lightweight champion 1942-44), born in Waynesboro, Georgia (d. 2000)
- Apr 1 Douglas Allenbrook, American pianist, harpsichord player, and composer, born in Alton, Massachusetts (d. 2003)
- Apr 1 Ken Reardon, Canadian Hockey Hall of Fame defenseman and executive (Stanley Cup 1946; NHL All-Star 1946-50; Montreal Canadiens), born in Winnipeg, Manitoba (d. 2008)
- Apr 1 Steve Race, British composer, jazz pianist and radio and television presenter (BBC's "My Music", 1967-94), born in Lincoln, England (d. 2009)
- Apr 1 William Bergsma, American composer (The Fortunate Islands; The Murder of Comrade Sharik), and educator (Juilliard, 1946-63; University of Washington, 1963-86), born in Oakland, California (d. 1994)
- Apr 3 Robert Karvelas, American actor (Get Smart - "Larabee"), born in NYC, New York (d. 1991)
- Apr 4 Willem J "Wim" the Villiers, South African minister of Administration
- Apr 5 Christopher Hewett, British actor (Mr. Belvedere; The Producers) and theater director, born in Worthing, Sussex, England (d. 2001)
- Apr 5 Les Jackson, English cricket fast bowler (2 Tests, 7 wickets; Derbyshire), born in Whitwell, England (d. 2007)
- Apr 5 Patricia Ford, Lady Fisher, Irish politician and founder (British Women Caring Trust), born in Donaghadee, County Down, Ireland (d. 1995)
- Apr 6 "Big" Walter [Horton], American blues harmonica player (Everybody's Fishin'), born in Horn Lake, Mississippi (d. 1981)
- Apr 6 Andrew Imbrie, American contemporary classical composer, and pianist, born in New York City (d. 2007)
- Apr 6 Franta Belsky, Czecg-British sculptor, born in Brno, Czechia (d. 2000)
- Apr 6 Lord Moore of Wolvercote [Philip Brian Cecil Moore], Private Secretary to the Sovereign (UK)
- Apr 8 Jan Novák, Czech classical composer, born in Nová Říše, Morovia (d. 1984)
- Apr 9 Frankie Thomas, American actor and author (Tom Corbett Space Cadet), born in NYC, New York (d. 2006)
- Apr 9 Jean-Marie Balestre, French president of motor sport's FIA, born in Saint-Rémy-de-Provence, France (d. 2008)
- Apr 9 Yitzhak Navon, President of Israel (1978-83), born in Jerusalem, British Mandate of Palestine (d. 2015)
- Apr 10 Chuck Connors, American author, actor (The Rifleman, Branded, Cowboy in Africa), professional basketball and baseball player, born in Brooklyn, New York (d. 1992)
- Apr 10 Peter Herbert Penwarden, English priest, born in Walthamstow, England (d. 1995)
- Apr 10 Sheb Wooley, American vocalist ("The Purple People Eater"), born in Erick, Oklahoma (d. 2003)
- Apr 11 Jeff Stollmeyer, Trinidad and Tobago cricketer (WI batsman pre/post-war), born in Santa Cruz, Trinidad (d. 1989)
- Apr 11 Jim Hearn, American baseball player, born in Atlanta, Georgia (d. 1998)
- Apr 11 Martin Buckmaster, 3rd Viscount Buckmaster, British diplomat
- Apr 12 Alfred Mabbs, British archivist (Public Records Office), born in London (d. 2009)
- Apr 13 Hans Heinrich Thyssen-Bornemisza, Dutch-Swiss industrialist, born in Scheveningen, Netherlands (d. 2002)
- Apr 13 Maxwell Henley Harris, Australian poet and publisher (Gift of Blood), born in Adelaide, Australia (d. 1995)
- Apr 14 Rosanell Eaton, American voting rights advocate, born near Louisburg, North Carolina (d. 2018)
- Apr 14 Thomas Schelling, American economist, (Nobel Prize 2005 - game-theory analysis), born in Oakland, California (d. 2016)
- Apr 15 Georgy Beregovoy, Soviet cosmonaut (Soyuz 3), born in Fedorivka, Poltava Oblast, Ukrainian Soviet Socialist Republic (d. 1995)
- Apr 16 Peter Ustinov, British actor, author, journalist, comedian and broadcaster (Death on Nile, Logan's Run, Billy Budd), born in London, England (d. 2004)
- Apr 19 Glyn England, British electrical engineer and CEO (CEGB, Windcluster Ltd), born in Llantrisant, Cardiff, South Wales (d. 2013)
- Apr 19 Will Ogdon, American composer, born in Redlands, California (d. 2013)
- Apr 20 Donald Gunn MacRae, sociologist, born in Glasgow (d. 1997)
- Apr 20 Janine Sutto, French Canadian actress and comedian (Guide de la petite vengeance), born in Paris, France (d. 2017)
- Apr 21 Jack Fletcher, American actor (Calucci's Department, Once Upon a Mattress), born in Forest Hills, New York (d. 1990)
- Apr 22 Cándido Camero, Cuban American percussionist (congo drum) and bandleader, born in Havana, Cuba (d. 2020) [1]
- Apr 22 Philip "Gabby" Pahinui, Hawaiian slack-key guitarist and singer, born in Honolulu, Territory of Hawaii (d. 1980)
- Apr 23 Janet Blair [Martha Janet Lafferty], American singer and actress (Leave it to the Girls, Smith Family), born in Altoona, Pennsylvania (d. 2007)
Warren Spahn (1921-2003)
Apr 23 American Baseball Hall of Fame pitcher (17 × MLB All-Star; World Series 1957; Cy Young Award 1957; 8 × NL wins leader; Boston/Milwaukee Braves), born in Buffalo, New York
- Apr 24 Laci Boldemann, Swedish composer, born in Helsinki, Finland (d. 1969)
- Apr 25 Jean Mogin, Belgian poet (Pastures of Silence), and playwright, born in Brussels, Belgium (d. 1986)
- Apr 25 Karel Appel, Dutch painter (Vragende Children), born in Amsterdam (d. 2006)
- Apr 26 Jimmy Giuffre, American jazz clarinetist, composer, arranger, and proponent of "free improv" jazz, born in Dallas, Texas (d. 2008)
- Apr 26 Margaret Gowing, English historian (Independence and Deterrence: Britain and Atomic Energy), born in Kensington, London (d. 1998)
- Apr 28 Rowland Evans, American news reporter (CNN-Evans & Novak), born in Whitemarsh, Pennsylvania (d. 2001)
- Apr 29 Cornelis de Jager, Dutch astronomer (Sun), born in Den Burg, Texel, Netherlands
- Apr 29 Tommy Noonan, American actor, screenwriter and producer (Gentlemen Prefer Blondes, Promises Promises), born in Bellingham, Washington (d. 1968)
- Apr 30 Roger L. Easton, American scientist and inventor (GPS), born in Craftsbury, Vermont (d. 2014)
About April 1921
How Old? 101 years old
Generation: Greatest Generation
Leap Year: No