Best known for producing and hosting the Ancient Aliens documentary television series, this TV personality and writer maintained a passionate belief in the pseudo-scientific theory that alien astronauts made contact with early humans.
He studied communications and sports journalism at New York's Ithaca College and went on to direct The Center for Ancient Astronaut Research.
As a young man, he worked in the publicity department of the International Federation of BodyBuilding and Fitness (IFBB).
He was born in Switzerland to Greek parents, and is fluent in five languages.
He and Church of Scientology founder L. Ron Hubbard shared a fascination with aliens.