- May 1 Paul Daels, president (Flemish Iron Pilgrimage committee)
- May 2 Satyajit Ray, Indian director (Goddess, Adversary), born in Calcutta, India (d. 1992)
- May 3 Joe Ames, American singer and actor (The Ames Brothers Show), born in Malden, Massachusetts (d. 2007)
Sugar Ray Robinson (1921-1989)
May 3 American boxer (world welterweight champion 1946-51; middleweight champion 1951-52, 55, 58), born in Ailey, Georgia
- May 3 Vasco Gonçalves, Portuguese army officer and 103rd Prime Minister of Portugal (1974-75), born in Lisbon, Portugal (d. 2005)
- May 4 Edo Murtić, Croatian painter, born in Velika Pisanica, Bjelovar, Croatia (d. 2005)
- May 4 John van Kesteren, Dutch tenor (Komische Oper, West-Berlin), born in The Hague, Netherlands (d. 2008)
- May 4 Virginia "Patsy" Garrett, American singer (Fred Waring's Pleasure Time), and actress (Nanny & the Professor), born in Atlantic City, New Jersey (d. 2015)
Arthur Leonard Schawlow (1921-1999)
May 5 American physicist who shared the 1981 Nobel Prize in Physics for his pioneering work with lasers, born in Mount Vernon, New York
- May 5 Sonja Oosterman, Dutch singer (Marketensters) (d. 2008)
- May 6 Alan Dewitt, American actor (It's About Time), born in Canton, Ohio (d. 1976)
- May 6 Erich Fried, Austrian-British writer, born in Vienna (d. 1988)
- May 6 Freddy Randall, English jazz trumpeter, born in London (d. 1999)
- May 6 Robert Fell, British CEO (British Stock Exchange)
- May 7 Gale Robbins [Betty Gale Murphy], American singer and actress (Fuller Brush Girl; Mr Hex), born in Chicago, Illinois (d. 1980)
- May 8 Graham Leonard, Bishop of London, most senior Anglican to convert to Catholicism since the reformation (d. 2010)
- May 9 Daniel Berrigan, American Jesuit priest and peace activist (Vietnam War), born in Virginia, Minnesota (d. 2016)
- May 9 Mona Van Duyn, American poet (d. 2004)
- May 9 Sophie Scholl, German anti-Nazi political activist, active in the non-violent resistance group, the White Rose (Die Weisse Rose), born in Forchtenberg, Germany (d. 1943)
- May 11 Hildegard Hamm-Brücher, German politician, born in Essen, Germany (d. 2016)
- May 11 Ian Percival, British politician (C) and Solicitor General (d. 1998)
- May 12 (Otis W.) "Joe" Maphis, American session and country music guitarist ("Dim Lights"), born in Suffolk, Virginia (d. 1986)
- May 12 Edvard Mirzoyan, Armenian composer, born in Gori, Georgia (d. 2012)
- May 12 Farley Mowat, Canadian writer and naturalist, born in Belleville, Ontario, (d. 2014)
- May 12 Giovanni Benelli, Italian archbishop (Florence) and Papal candidate
- May 12 Henry Mackie, designer of the Belfast Calorimeter
- May 12 Joseph Beuys, German avant-garde painter (Fluxus, movement), born in Krefeld, Germany (d. 1986)
- May 13 Syd[ney G] Vincent, British mine workers leader
- May 14 Arve Opsahl, Norwegian actor and stand-up comedian (Mot i brøstet, Olsen-banden), born in Oslo, Norway (d. 2007)
- May 16 Harry Carey Jr, American actor (Back to the Future Part III, Gremlins), born in Saugus, California (d. 2012)
- May 16 Robert Croften Brown, politician
- May 17 Bob Merrill, American composer and lyricist (People, Mambo Italiano), born in Atlantic City, New Jersey (d. 1998)
- May 17 Dennis Brain, British classical horn player (Serenade), born in London, England (d. 1957)
- May 17 John Garlick, British senior civil servant
- May 18 Anthony Epstein, English pathologist and virologist (Epstein–Barr virus)
- May 19 Daniel Gélin, French actor (Obsession, The Man Who Knew Too Much), born in Angers, Maine-et-Loire (d. 2002)
- May 19 Karel van het Reve, Dutch writer, translator, and Russian literature historian (Comrade's Religion), born in Amsterdam, Netherlands (d. 1999)
- May 19 William H. Stewart, 10th US Surgeon General (1965-69), born in Minneapolis, Minnesota (d. 2008)
- May 20 Hal Newhouser, American Baseball HOF pitcher (7 × MLB All-Star; World Series 1945; AL MVP 1944, 45; Triple Crown 1945; Detroit Tigers), born in Detroit, Michigan (d. 1998)
- May 20 John Harrison, British vice admiral/surgeon
- May 20 John Marchi, US Senator (Rep-R-NY 1957-2006), born in Staten Island, New York (d. 2009)
- May 20 Wolfgang Borchert, German writer, born in Hamburg (d. 1947)
Andrei Sakharov (1921-1989)
May 21 Russian nuclear physicist and an activist for disarmament, peace and human rights (Nobel 1975), born in Moscow, Russia
- May 21 Leona Wood, painter and dancer, born in Seattle, Washington
- May 23 Humphrey Lyttelton, British jazz trumpeter and bandleader ("Bad Penny Blues"), and broadcaster (BBC2 - Best Of Jazz, 1967-2007; BBC4 - I'm Sorry I Haven't A Clue, 1972-2008), born in Eton, Buckinghamshire (d. 2008)
- May 23 James [Benjamin] Blish, US/UK, sci-fi author (Hugo, Star Trek Reader)
- May 23 Loren Tindall, American actor (Meet Me on Broadway, Girl of Limberlost), born in Hastings, Oklahoma (d. 1973)
- May 23 Montague Modlyn, broadcaster
- May 23 Sanderson Temple, circuit judge
- May 25 Hal David, American lyricist ("Raindrops Keep Fallin' On My Head"; "What The World Needs Now Is Love";"Do You Know the Way to San Jose"), born in Brooklyn, New York (d. 2012)
- May 25 Jack Steinberger, American physicist (1988 Nobel Prize for Physics - Neutrinos), born in Bad Kissingen, Germany (d. 2020) [1]
- May 25 Kitty Kallen, American singer ("Little Things Mean a Lot"), born in Philadelphia, Pennsylvania (d. 2016)
- May 26 Frank Mooney, New Zealand cricket wicketkeeper (13 Tests, 30 dismissals; Wellington), born in Wellington, New Zealand (d. 2004)
- May 27 Caryl Chessman, kidnapper who got death penalty (1960)
- May 28 Heinz G. Konsalik, German author (d. 1999)
- May 28 Tom Uren, Australian politician, Australian heritage and conservation campaigner, born in Sydney, New South Wales (d. 2015)
- May 29 George Terry, British chief constable (Sussex, England) (d. 1995)
- May 31 Alida Valli [Baroness Alida von Marckenstein-Frauenberg], Italian actress (The Paradine Case, The Third Man), born in Rome, Italy (d. 2006)
- May 31 Andrew Grima, Italian-born British jeweller known for his modern designs, born in Rome, Italy (d. 2007)
- May 31 Howard Reig, American radio and television announcer
- May 31 Robert Arthur Ley, English sci-fi author (Telepath, Power of X) (d. 1968)
About May 1921
How Old? 101 years old
Generation: Greatest Generation
Leap Year: No