I hear Chris Gaines used to sing country.
Neil Young can do any style of music.
Frank Zappa first wrote weird doo-wop songs and eventually became the greatest guitar player in the world, rocking like no other. Then he settled down (sort of) to composing orchestral pieces and jazz songs that humans couldn’t play.
Slayer started out nearly 30 years ago as a proto-thrash metal band, and now they are, um, well, still THE proto-thrash metal band. SLAYERRRRRRRR!
Miles Davis was in the center of many new jazz styles, from cool through fusion. Until the last year of his life he never (publicly) looked back.
U2 started out as a primarily Christian rock band.
Mark Mothersbaugh of the new wave? band Devo also has a successful career as a jazz/classical composer, particularly for film and televison. There is a lot of crossover in his work but the uninitiated would be hard pressed to guess that Whip It and Mothersbaugh’s Canon were written by the same person.
He is one of my favorite composers.
\m/ friggin’ right \m/
They owe me a show. They had to reschedule because of Tom’s back surgery. I haven’t heard the new stuff so it gives me more time to get caught up.
Springsteen went from the poster boy for gut bucket traditional story-based rock and roll to drum machines to wretchedly self indulgent Woody Guthrie inspired pap.
In Loggins and Messina Kenny Loggins played folk, easy listening, and some country rock. When he went solo he played mostly rock. Then, in the 90’s, he kind of went new-agy.
Seems like a lot of artists have changed their styles. I don’t know why I thought this would be a rare occurrence. I guess if a talented artist decides they want to do something different more than likely they’ll continue to be successful.
Olivia Newton-John was a champ at this. She started out singing bubblegum with the group Toomarrow, then switched to Folk Music, “If Not For You” (Bob Dylan Remake), and “Banks Of The Ohio.” Then she moved to Country Music then she popularized the second most annoying trend in female music (after screeching) that breathless style of singing, most notably on her number one hit “Have You Never Been Mellow.”
Then she switched to A/C then back to mainstream pop after Grease and she ushered in the mini-Australian invasion of the early 80s.
Sheena Easton moved from mainstream pop “Morning Train (Nine To Five)” to R&B with her #2 smash hit “The Lover In Me.” Two of her last two MCA Ds “The Lover In Me” and “What Comes Naturally” were almost all R&B.
Juice Newton was another one that was all over the map. From fairly hard rock in the beginnig to mainstream pop to ballads then back to country. Indeed I remember a review in Rolling Stone of Juice’s album “Dirty Looks” where it said the singer was gifted and but the album was so far all over the map it was impossible to classify what type of music she did.
As for the OP who brings up Mariah Carey she has a great voice and needs to be told SCREECHING ISN’T SINGING 
David Bowie! He can do anything! My favourite albums of his are 25 years apart.
Genesis??!?
Gensis commercialized sell-out pop band become has!.
But in the process they did expand their fan base from a cult of eager music loving heads filling auditoriums to pop fans filling stadiums. I think most of the original heads gave up on them; at least I did.
Peaches en Regalia…at 1:07 it goes straight from a pompous jazz-fusion symphony to the theme song of some mid-1970s cop show. Love it!
And Ricky Gervais went from Seona Dancing to “Freelove Freeway”!
Ritchie Blackmore: from hard blues-rock guitar god and general bad boy to renaissance troubador. (with an assist from the lovely Candice Night)
And country, both early in her solo career, and with Emmylou Harris and Dolly Parton, among many others that she’s recorded with, and now back to folk again with Ann Savoy.
No, not really. I assume you’re referring to Cruising With Ruben & The Jets, which was a parody of the genre. The four albums he released prior to that one were definitely not doo-wop.
Todd Rundgren changes his style with every album.
King Crimson, to a lesser degree.
Danny Elfman - from Oingo Boingo frontman to the upper tier of film-scoring.
Has a rap artist made the jump to something radically different? I imagine there’s been cases where they’ve jumped to R&B. I know Kid Rock started with the rap/rock thing but he’s actually sang in some of them! Same goes for the Limp Bizkit dude.