Ludovic Lazarus (Ludwik Lejzer) Zamenhof (15 December 1859 - 14 April 1917) was a Jewish-Polish eye doctor and scholar who created the international language Esperanto.

Zamenhof was born in 1859 in the town of Białystok, Poland. At the time, Poland was a part of the Russian Empire. Bialystok contained three major groups: Poles, Belorussians, and Yiddish-speaking Jews. Zamenhof thought that one common language would join these groups and stop fights between them.

His first language was said to be Polish. His parents spoke Russian and Yiddish in the home. His father was a German teacher, so Zamenhof learned that language from an early age. Later he learned French, Latin, Greek, Hebrew and English. He also had an interest in Italian, Spanish and Lithuanian.

Zamenhof decided that the international language must have a simple grammar and be easier to learn than Volapuk, an earlier international language. The basics of Esperanto were published in 1887.