- May 4 Viktor Kingissepp, Estonian Bolshevik politician (b. 1888)
- May 7 Max Wagenknecht, German composer, dies at 64
- May 18 Charles Louis Alphonse Laveran, French physician (Nobel Prize in Physiology or Medicine, 1907), dies at 76
- May 19 Heinrich Quincke, German internist and surgeon (postural drainage), dies at 79
- May 21 Sidney Ainsworth, British silent film actor (Not in the News, The Rajah's Tunic), dies at 49
- May 22 Ada Jane Jones, English-American popular singer, among the earliest Female singers to be recorded, dies of kidney failure at 48
- May 28 John Munro Longyear, American capitalist and developer of timber and mineral lands, dies at 72
- May 28 Carl Teike, German military composer, dies at 58
- May 29 Yevgeny Vakhtangov, Armenian-Russian theatrical director of the Moscow Art Theatre (Vakhtangov Theatre), dies of cancer at 39
- May 30 David Mendes Chumaceiro, Curacaos poet (Adelfas), dies at 45