- Apr 3 Leon Michel Gambetta, French attorney and 37th Prime Minister of France (1881-82), born in Cahors, Kingdom of France (d. 1882)
- Apr 5 Alpheus Hyatt, American zoologist and paleontologist, born in Washington, D.C. (d. 1902)
- Apr 11 Joseph Leopold Röckel, German composer, born in London (d. 1908)
- Apr 12 John Shaw Billings, American librarian and surgeon, born in Allensville, Switzerland County, Indiana (d. 1913)
- Apr 16 Karel Bendl, Czech composer, born in Prague (d. 1897)
- Apr 18 Paul-Émile Lecoq de Boisbaudran, French scientist, born in Cognac, France (d. 1912)
John Muir (1838-1914)
Apr 21 Scottish naturalist and discoverer (glaciers in High Seirras), born in Dunbar
