- May 4 Camille Pleyel, Austrian piano builder, and composer, dies at 66
- May 5 Sir Robert Inglis, Bt, English politician (b. 1786)
- May 15 Jan Mazereeuw, Frisian farmer/sect leader, dies at 75
- May 23 Charles Robert Malden, British naval officer (discoverer of Malden Island, central Pacific), dies at 57
- May 27 Nikolaj Bestuzhev, Russian Navy officer, writer and painter (Decembrist revolt), dies at 64
- May 30 Ahmad Pasha Bey, 10th Husainid Bey of Tunis, (1837–1855) who abolished slavery, dies at 49