Actor Don Grady, who played big brother Robbie on the long-running TV sitcom My Three Sons, has passed away from cancer at 68.

Grady was a musician and singer who, like Justin Timberlake and Britney Spears, got his start in television on The Mickey Mouse Club as a Mouseketeer. As Robbie on My Three Sons, which ran from 1960-’72, he appeared in more than 300 episodes, and soon became a heartthrob, appearing on the cover of numerous teen magazines.

Grady also appeared in other shows, including The Rifleman and Wagon Train, and formed a pop singing group, the Yellow Balloon. He is survived by his wife and two children.