- May 1 Guido Gezelle, Flemish priest and poet, born in Brugge, Belgium (d. 1899)
- May 1 Mother [Mary Harris] Jones, American labor organizer (cofounded Industrial Workers of the World), born in Cork City, Ireland (d. 1930)
- May 5 John Batterson Stetson, American hat manufacturer, born in Orange, New Jersey (d. 1906)
- May 10 François-Marie Raoult, French physicist and chemist (law of Raoult), born in Fournes, France (d. 1901)
- May 11 John Converse Starkweather, American Brigadier General (Union Army), born in Cooperstown, New York (d. 1890)
- May 13 Zebulon Baird Vance, American politician (Senator and Governor of South Carolina 1862-65, 77-79, and Confederate officer, born in Reems Creek, North Carolina (d. 1894)
- May 14 George Pierce Doles, Brigadier General (Confederate Army), (d. 1864)
- May 15 Laurence Simmons Baker, Brigadier General (Confederate Army), (d. 1907)
- May 18 (Károly) "Karl" Goldmark, Hungarian-Viennese violinist and composer (Rustic Wedding Symphony; The Queen of Sheba; Sakuhtala), born in Keszthely, Kingdom of Hungary (d. 1915)
- May 20 Amalia of Saxen-Weimar-Eisenach, Dutch princess and wife of Prince Henry of the Netherlands, born in Walferdange, Luxembourg (d. 1872)
- May 20 Hector Malot, French writer (Without Family), born in La Bouille, France (d. 1907)
- May 24 Alexei Savrasov, Russian painter, born in Moscow, Russia (d. 1897)
- May 25 Jules de Geyter, Belgian poet (International), born in Lede, Belgium (d. 1905)
- May 28 Carl Filtsch, Transylvanian child piano prodigy, and composer, born in Mühlbach (Sebeș), Romania (d. 1845)
- May 28 George Lucas Hartsuff, American Major General (Union Army), born in Tyre, New York (d. 1874)
- May 30 Edward Winslow Hinks, American Brevet Major General (Union Army), born in Bucksport, Maine (d. 1894)
20-29
30-39
40-49
50-59
80-89
Over 90