• Born date: 1859-12-15
  • Born in: Russian empire
  • Death date: 1917-04-14
  • Death in: Kingdom of Poland (1916–18)
L. L. Zamenhof

Ludwik Lazarus Zamenhof (15 December 1859 – 14 April 1917) was the creator of Esperanto, the world's most successful constructed language, and a physician by profession. 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 language which he first developed in 1873 while still in school.