- Apr 3 Conrad Veidt, German actor (Casablanca, Cabinet of Dr Calgary), dies from a heart attack at 50
- Apr 4 Oskar Schlemmer, German painter, sculptor and choreographer (Triadisches Ballett), dies at 54
- Apr 4 Raoul Laparra, French composer, dies during a bombing raid in WWII at 66
- Apr 4 Hartzell "Tiny" Parham, American jazz pianist, theater organist, and bandleader, dies at 43
- Apr 5 Aleš Hrdlička, Austro-Hungarian anthropologist and curator (US National Museum), dies at 74
- Apr 7 Jovan Ducic, Serbian poet (Blue Legends), dies at 72
- Apr 7 Alexandre Millerand, President of France (b. 1859)
- Apr 8 Paul Colin, Belgian journalist/collaborator, executed
- Apr 8 Richard Sears, American tennis player (US Nat C'ship 1881-87), dies at 81
- Apr 14 Asser B. Kleerekoper, Dutch SDAP-Second-Member of parliament, dies at 62
- Apr 14 Geoffrey Turton Shaw, British organist, composer, and educator, dies at 63
Isoroku Yamamoto
Apr 18 Isoroku Yamamoto, Japanese WWII Marshall Admiral & Commander-in-Chief of the Japanese fleet who led the attack on Pearl Harbor, killed in action at 59 by a US ambush after the "Magic" code-breaking team intercepted and decoded his flight plan
- Apr 19 Alexander Schmorell, German resistance fighter, beheaded
- Apr 19 Gustave Doret, Swiss composer, dies at 76
- Apr 19 Willy Graf, German resistance fighter, beheaded
- Apr 24 Gerardus H de Hare, socialist vicar, dies at 63
- Apr 25 Vladimir Ivanovich Nemirovich-Danchenko, playwright/director, dies
- Apr 29 Joseph Achron, Latvian violinist and composer (Golem suite), dies at 56
- Apr 29 Karl Adrian Wohlfart, Swedish composer, dies at 68
- Apr 29 Sidney Keyes, English poet (Foreign Gate), dies fighting during WWII at 20
- Apr 30 Beatrice Potter Webb, British sociologist, economist (founded London School of Economics) and writer (My Apprenticeship), dies at 85
- Apr 30 Etty Hillesum, Dutch diarist, dies in Auschwitz
- Apr 30 Otto Jespersen, Danish linguist, dies at 82
- Apr 30 Leo Smit, Dutch composer, dies in Sobibór extermination camp at 42