Mark Rosenfelder is a famous conlanger and conworlder. He created the fantasy world Almea with many well-elaborated conlangs, of which Verdurian is the most thoroughly worked out one.
He is also the head admin of the Zompist Bulletin Board.
Notable modern conlangers: David J. Peterson * Marc Okrand * Mark Rosenfelder
Historically significant conlangers: Hildegard von Bingen * J. R. R. Tolkien * L. L. Zamenhof
General Conlangers: Bjorn Bakker * Danny Wier * "Millsaic"