Don Louis Agrati (June 8, 1944 – June 27, 2012), better known as Don Grady, was an American television, and movie actor, composer, and musician. He was best known both as one of Mickey Mouse's original "Mouseketeers", and as Robbie Douglas on "My Three Sons". His sister was also an actress, billed as Lani O'Grady. Their father was Lou A. Agrati. Their mother was a talent agent, known as Mary Grady. 