An original Mickey Mouse Club Mouseketeer on, Grady was well-known for his role as frustrated middle brother Robbie Douglas on My Three Sons. one of the sons in. His other credits include a handful of Westerns — The Restless Gun, The Rifleman and Wagon Train, among them — as well as the NBC series The Eleventh Hour.
Following his long-running stint on Sons, Grady turned to music. He composed the music for the film Switch and for The Phil Donahue Show. In 2008, he released an album about the baby boomer generation called Boomer: JazRokPop.
Grady is survived by his wife Ginny and their two children, Joey and Tessa.