- Apr 10 Joseph-Louis Lagrange, Italian mathematician and astronomer (number theory, celestial mechanics), dies at 77
- Apr 14 Joachim Nicolas Eggert, composer, dies at 34
- Apr 19 Benjamin Rush, physician/abolotionist (signed Declaration of Independence), dies at 67
- Apr 27 Zebulon Pike, American brigadier general and explorer (Pike's Peak), dies in battle at 34
- Apr 28 Mikhail Illarionovich Kutuzov, Russian field marshal (b. 1745)
- Apr 29 Christian Danner, composer, dies at 55