L. L. Zamenhof
![](/Images/godic/202502/21/1908-kl-t-zamenhof4322.jpg")
![Zamenhof, around 1879](/Images/godic/202502/21/Zamenhof-18794322.jpg")
![Zamenhof at his desk in Warsaw apartment, 1910](/Images/godic/202502/21/1910-Universo-p322-llzdet4322.jpg")
![Zamenhof speaking at the World Esperanto Congress in Barcelona (Spain) in 1909.](/Images/godic/202502/21/-Ludwik_Zamenhof_speaking.ogg4322.jpg")
Ludwik Lejzer Zamenhof (Polish:Ludwik Łazarz Zamenhof, 15 December [O.S. 3 December] 1859–14 April [O.S. 1 April] 1917), usually credited as L. L. Zamenhof, was a Polish ophthalmologist, inventor, and writer. He is most widely known for creating Esperanto, the most successful constructed language in the world. He grew up fascinated by the idea of a world without war and believed that this could happen with the help of a new international auxiliary language, which he first developed in 1873 while still in school.