- May 1 George Inness, American landscape painter (Delaware Water Gap), born in Newburgh, New York (d. 1894)
- May 4 Augustus Le Plongeon, French-American photographer and antiquitarian, born in Island of Jersey, France (d. 1908)
- May 4 Thomas Henry Huxley, English biologist (comparative anatomy), born in Ealing, Middlesex, England (d. 1895)
- May 6 Joseph Bailey, American civil engineer and Brevet Major General (Union Army), born in Morgan County, Ohio (d. 1867)
- May 8 George Bruce Malleson, English officer in India and author, born in Wimbledon, London (d. 1898)
- May 10 Rudolf Viole, German pianist and composer, born in Schochwitz, Germany (d. 1867)
- May 20 Antoinette Brown Blackwell, American minister (1st ordained US female minister), born in Henrietta, New York (d. 1921)
- May 21 George Lafayette Beal, American politician and Brevet Major General (Union Army), born in Norway, Maine (d. 1896)
- May 26 Felipe Gutiérrez Y Espinosa, Puerto Rican composer, born in San Juan, Puerto Rico (d. 1899)
- May 29 David Bell Birney, American businessman, lawyer, and Major General (Union Army), born in Huntsville, Alabama (d. 1864)
20-29
30-39
40-49
50-59
80-89
Over 90