That is, people who are best known / first became famous as actors, but can also sing like a professional:
Katey Sagal (best known as Peg Bundy from Married... with Children)
John Schneider (best known as Bo Duke from The Dukes of Hazzard)
Ja'Net DuBois (best known as Willona Woods from Good Times)
Cecily Strong (best known as an SNL cast member)
Eddie Murphy (best known as an SNL cast member and movie star)
Hugh Jackman
Neil Patrick Harris
https://www.youtube.com/watch?v=LqJxyuTMMog
Jack Black
Patrick Wilson
The actress from the StarWars sequels. Daisy Ridley.
shareZooey Daschenel has done a few records as part of a duo, She and Him. It's sort of laid back, 70s pop in a Carpenters vein.
shareMaybe not as good as professionals, but
Reese Witherspoon
Keira Knightley
Marion Cotillard
Anna Kendrick
Joaquin Phoenix
Jim Carrey
Jamie Foxx
Anna Kendrick for sure; she's easily up there with professionals. Witherspoon and Phoenix weren't bad in that Johnny Cash movie, but it was hard to gauge their actual singing talent because they were trying to mimic Cash and Carter's singing rather than singing naturally. I've never heard the others you mentioned sing.
shareAlso in Walk The Line they had a ton of autotune on their voices, so it's hard to tell..
Jim Carrey definitely has the chops, but I haven't heard him take on anything serious. :D
https://www.youtube.com/watch?v=7MoWQSe3txY
https://www.youtube.com/watch?v=SIz-V2fcinQ
Jim Carrey being able to sing doesn't surprise me, since he can do good celebrity impressions, and singing is the same idea, i.e., being able to manipulate your voice particularly well. For the same reason, it isn't surprising that Eddie Murphy can sing.
And speaking of comedians who can sing, Jim Breuer can too. If you haven't heard him listen to the song he recorded with AC/DC's Brian Johnson: "Mr. Rock 'n' Roll" - https://youtu.be/98B_J6prjnI
Daisy Ridley is a professionally trained singer. Barbra Streisand rates her singing ability " She can sing ! " But like so many actors who can sing she almost never gets the chance to:
https://www.youtube.com/watch?v=urhgv3W0VxA