He was Uncle Charlie
William Demarest (February 27, 1892 – December 27, 1983).
Carl William Demarest was an American character actor, known for playing Uncle Charley in My Three Sons. He became a prolific film and television actor, appearing in over 140 films, beginning in 1927 and ending in the 1970s. He frequently played crusty but good-hearted roles. Demarest has a star on the Hollywood Walk of Fame for his contributions to motion pictures, bestowed upon him on August 8, 1979, by the Hollywood Chamber of Commerce.
Demarest appears with Donna Reed in the Screen Guild Theater radio broadcast of "Hail the Conquering Hero" (1945); and the films (The Far Horizons (1955) and Pepe (1960).