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Don Grady, who played one of television's most iconic big brothers on the 1960s sitcom "My Three Sons," died Wednesday in Thousand Oaks, Calif. He was in hospice care, and eventually succumbed to cancer at age 68.

Grady was born Don Louis Agrati in San Diego before his career as a Mouseketeer on the "Mickey Mouse Club" at age 13. He later filled the role of Robbie Douglas on "My Three Sons," from 1960 to 1971. The sitcom starred the late Fred MacMurray as a widowed father raising his three sons.

Grady was also a composer, who wrote the theme for Phil Donahue's long-running daytime talk show.

A post on the Facebook page of Barry Livingston, who played Grady's brother Ernie on "My Three Sons," read, "He was an inspiration to me in so many ways, and his impact on my life is indelible. I will miss him greatly."

Grady had a deep passion for music and appeared with his own band, the Greefs, throughout the series. Livingston said music was Grady's true inspiration, and he believes "Don would love to be remembered for his great music as much as a teen idol and television icon," the Associated Press reported.