- May 2 Henry Martyn Robert, American soldier and parliamentarian (Robert's Rules of Order), born in Robertville, South Carolina (d. 1923)
Adam Opel (1837-1895)
May 9 German automobile manufacturer (founded Adam Opel AG), born in Rüsselsheim, Hesse, Prussia
- May 10 Pinckney Benton Stewart Pinchback, American politician and publisher (1st African American governor - Governor of Louisiana (R) 1872-73), born in Macon, Georgia (d. 1921)
- May 23 James Sanks Brisbin, American educator, lawyer, and Brevet Major General (Union Army), born in Boalsburg, Pennsylvania (d. 1892)
- May 23 Józef Wieniawski, Polish pianist, composer, conductor and teacher, born in Lublin, Poland (d. 1912)
Wild Bill Hickok (1837-1876)
May 27 American cowboy and scout, born in Troy Grove, Illinois
- May 27 Ivan Kramskoi, Russian painter and art critic, born in Ostrogozhsk, Voronezh Governorate, Russian Empire (d. 1887)
- May 27 Robert Hoke, American Major General (Confederate Army), born in Lincolnton, North Carolina (d. 1912)
- May 28 George Ashlin, Irish architect noted for his work on churches and cathedrals, born in County Cork, Ireland (d. 1921)
- May 28 Tony Pastor, American vaudeville performer, born in Manhattan, New York (d. 1908)
- May 29 Alexander de Savornin Lohman, Dutch minister and party leader (CHU), born in Groningen, Netherlands (d. 1924)
- May 29 Luca Fumagalli, Italian pianist and composer (Luigi XI), born in Inzago, Lombardo-Venetian Kingdom, Austrian Empire (d. 1908)
- May 31 Ernest Daudet, French journalist and writer (White Terror), born in Nîmes, France (d. 1921)
- May 31 Stephen Dodson Ramseur, American general and the youngest West Pointer to be Major General, born in Lincolnton, North Carolina (d. 1864)
- May 31 William Henry Fitzhugh Lee, American Major General (Confederate Army), born in Arlington House, Virginia (d. 1891)
20-29
30-39
40-49
50-59
80-89
Over 90