- May 6 George Sears Greene, American Brevet Major General (Union Army), born in Apponaug, Rhode Island (d. 1899)
- May 9 Samuel Cousins, English mezzotint engraver, born in Exeter, Devon, England (d. 1887)
- May 11 Henri Labrouste, French architect (d. 1875)
William H. Seward (1801-1872)
May 16 American politician (Secretary of State, 1861-69, Governor of New York, 1839-42), born in Florida, New York
- May 31 Johann Georg Baiter, Swiss philologist, born in Zürich, Switzerland (d. 1877)