I'd like to sing the praises of one of my favorites - Todd Rundgren. In addition to nearly 45 years of making albums, he's also been a producer/engineer for nearly that long. His first professional engineering gig was the "Stagefright" album for The Band. His most famous production job is of course Meatloaf's "Bat Out Of Hell" album, where he did all the vocal arrangements, played all the guitars, and recruited his Utopia bandmates as the studio band ( along with a couple of Springsteen's guys). He also produced Grand Funk ( twice), Hall & Oates, The Tubes ( twice), the New York Dolls debut, Cheap Trick, Steve Hillage, Felix Cavaliere, Shaun Cassidy, The Tom Robinson Band,Rick Derringer, XTC's masterpiece "Skylarking", Jill Sobule, and many others ( all this in addition to producing a few dozen of his own solo albums and Utopia albums).
He also was a video pioneer in the 70's. He actually was heavily invested in a proposed 24 hour satellite video channel in the late 70's. The satellite itself never got off the ground ( literally) and the project was scrapped. A couple of years later MTV was launched ( literally) and the rest is history.
He developed video graphic software in the mid-80's and was the first artist to release an album in the CD-I ( CD Interactive) format in the early 90's. The format never took off, but he was there first.
He's played countless benefit shows, telethons, and the occasional political fundraiser.
He wrote a musical based on the script that was written for the Beatles movie intended as the follow up to "Help!".
He wrote music for *** Wee's Playhouse and a handful of other TV shows and a few movie soundtracks, including Dumb And Dumber.
And then there's Liv Tyler. For the first dozen or so years of her life she was Liv Rundgren. Liv's mother, Bebe Buell was Todd's girlfriend through a big chunk of the 70's and Buell had an affair with Steven Tyler. At the time Liv was born, Steven Tyler was in no shape to be a father ( or much of anything else for that matter) so Todd committed to helping raise her. He provided for her and treated her as his own until she discovered that Tyler was her real father. They're reportedly still pretty close.