- May 3 Montgomery Cunningham Meigs, American Brevet Major General (Union Army), born in Washington, D.C. (d. 1892)
- May 14 Gualtiero Sanelli, Italian composer, born in Parma (d. 1861)
- May 16 Henry Hopkins Sibley, Brigadier General (Confederate Army), (d. 1886)
- May 24 Emanuel Leutze, American painter (Washington Crossing the Delaware), born in Schwäbisch Gmünd, Württemberg, German Confederation (d. 1868)
- May 24 Robert Seaman Granger, American Brevet Major General (Union Army), born in Zanesville, Ohio (d. 1894)