L. L. Zamenhof

Ludwik Lejzer Zamenhof (1859–1917) was a Polish physician and linguist who created Esperanto, the most successful constructed international language. He was also a pacifist and philosopher who developed a spiritual philosophy called Homaranismo, aiming for human unity and peace. Zamenhof published the first Esperanto grammar in 1887 under the pseudonym 'Dr. Esperanto'.