- May 2 Clara Immerwahr, German chemist, first woman to be awarded a doctorate in chemistry in Germany, dies at 44
Alfred Gwynne Vanderbilt (1877-1915)
May 7 American businessman (New York Central Railway), dies aboard the RMS Lusitania during World War I at 37
Anthony Wilding (1883-1915)
May 9 New Zealand tennis player (Wimbledon 1910-13), killed in action on the Western Front at 31
François Faber (1887-1915)
May 9 Luxembourgian cyclist (Tour de France 1909), killed in action by gunshot wounds at 28
- May 10 Albert Weisgerber, German painter and graphic artist, dies in battle at 37
- May 19 Bob Ferguson, Scottish golfer (British Open 1880, 81, 82), dies at 69
- May 19 John Simpson Kirkpatrick stretcher bearer with the Australian and New Zealand Army Corps at Gallipoli during World War I (b. 1892)
- May 21 Leonid Gobyato, Russian general (designed the portable mortar), dies in combat at 40