Phil Collins was a child actor, who became a drumming, keyboard playing, vocalist. Went back into acting for various pop videos, Spielberg's Hook (I believe) and some straight-to-video thing... leaving us wishing he really hadn't! On both counts, if you preferred Genesis under Gabriel.
I guess coming back to fame also counts if somebody else famous remembers you... like Stallone getting Lundgren in on the act for The Expendibles. And he did play "He-Man" in the Masters of the Universe film, which is in with those who were kids during the 1980's. Some claim to it.
Not that he was in Star Trek. That would be Frank Langella's Skeletor and Robert Duncan McNeill.
Now I'm just ramblin' like Granpa Simpson. Erm... what does GNDN stand for again?