Oswald Veblen (June 24, 1880 – August 10, 1960) was an American mathematician, geometer and topologist, whose work found application in atomic physics and the theory of relativity. He proved the Jordan curve theorem in 1905 and introduced the Veblen hierarchy of ordinals in 1908.
He is my academic great-great-great-great-grandfather. I am a tenured mathematics professor.