Ronnie James Dio is the only rock star I can think of who didn't find his voice until he reached his mid-30's. Most other rock stars have burned out by that age, or at least are on auto pilot (see Jagger, Mick; or Richards, Keith). He's also literally the oldest man to ever play metal, being born in 1942, and the only one who has musical roots about this far back.
Ironically, what got me listening again to the 50's rockers is the recent documentary about Lemmy from Motorhead. He was born in 1945, and in addition to a cool scene where he's store shopping for a Beatles mono box set, the conversation he was having with Dave Grohl about all the 50's rockers made me want to do further exploring, listen again to what I already have, and also wish I was in the room for that conversation.