A language spoken by millions of TV fans was invented from scratch by one linguist

When HBO needed a fully functional language for Game of Thrones' Dothraki horse-lords, it ran an open competition through the Language Creation Society. Linguist David J. Peterson won, and built Dothraki's grammar, sound system and vocabulary essentially from nothing, later expanding it into a spoken, taught language with its own courses and dictionaries. He's since built dozens more constructed languages for film and television.

— Wikipedia contributors, David J. Peterson — Dothraki language, Game of Thrones