- May 8 Marquis of Pombal, Prime Minister of Portugal (1756-1777), dies at 82
- May 15 Richard Wilson, Welsh landscape painter, dies at 67
- May 16 Daniuel Charles Solander, botanist, dies
- May 20 Carlo Giovanni Testori, composer, dies at 68
- May 20 Christoph Gottlieb Schroter, composer, dies at 82
- May 20 William Emerson, British mathematician (b. 1701)