- May 4 Charles Boucher de Boucherville, Premier of Quebec, born in Montreal, Quebec (d. 1915)
- May 10 August Ritter von Pettenkofen, painter
- May 13 Francis of Assisi of Bourbon, King Consort of Spain (d. 1902)
- May 16 Eduard Hille, Dutch composer/conductor
- May 20 Emile Erckmann [E-Chatrian], French writer (Waterloo)
- May 20 Frederic Passy, French economist/pacifist (Nobel 1901)
- May 21 Dabney Herndon Maury, Major General (Confederate Army), (d. 1900)
- May 21 Mosby Monroe Parsons, United States officer in the Mexican–American War and brigadier general of the Confederate States Army, born in Charlottesville, Virginia (d. 1865)
- May 26 Edmond de Goncourt, French writer, wrote with his brother Jules de Goncourt, born in Nancy (d. 1896)
- May 27 Henry Wylde, English composer and conductor, born in Bushey, Hertfordshire (d. 1890)
- May 27 Joachim Raff, German-Swiss composer, born in Lachen, Switzerland (d. 1882)