The Blues Brothers
John Belushi and Dan Ackroyd were Joliet Jake and Elwood Blues. First, on Saturday Night Live (1975), then on a concert tour (1979), then in their own movie (1980). There was also a book based on the movie. They released 2 or 3 albums, plus a "best of" compilation. Their back up band was a veritable who's who of R&B session men.
Then, a scant 18 years later, Dan Ackroyd said to himself, "You know, I suck. But I don't suck enough. I must ruin people's one remaining good memory of me." And that's how Blues Brothers 2000 got made. True story!