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