Movie Stars that can handle musical instrument well

Myles Teller looked pretty realistic as a drummer in Whiplash.

Dudley Moore was quite the classic pianist. The disease that took him impaired his playing.. His only complaint.

That guy was so funny.. Liza Minnelli, Dudley Moore and the super straight man's man Sir Arthur John Gielgud. In "Arthur"

Steve Martin

Monica played wild Willies and Wild Willie played the Sax. He was quite the actor after he got caught. "I'm sorry". CRAP I wouldn't be.. Have you looked at Hillary? One of the male aids would have been a one up.. Really..

No dear, I'll wear the blind fold and you'll have to tie me up..

Regards

Glad someone noted Steve Martin. His comedy acts nearly as good as his banjo skill.

Woody Allen -clarinet

Anyone remember this appearance of that "wild and crazy guy?"
https://www.youtube.com/watch?v=prbGlOhB7Ss

Steve actually is an accomplished player, but I thought this now corny appearance  was refreshing.

Speaking of banjo, the late George Siegel.
Hugh Laurie... piano, guitar.

Charlie Chaplin as a composer plus Chico and Harpo Marx as instrumentalists.

One of my early heroes, Steve Allen
STEVE ALLEN teaches jazz piano - Bing video

And, the maestro award goes to...

https://www.youtube.com/watch?v=010aaw1Ajo0

DeKay

Jeff Daniels knows his way around a guitar

Russell Crowe has a jam-band as does Keanu Reeves...

Johnny Depp, another guitar player.

Least we forget...

The KING of Guitar:

https://www.youtube.com/watch?v=pJXbM-o76TM

DeKay

Amateurs! https://www.youtube.com/watch?v=_c_ufaxeSTs  

Russel Crowe plays smallest part in "his" band, because it's mostly pro musicians that you can give credit to, but definitely-most-definitely you can't give him credit neither for singing or playing 2...3 chords on guitar.

Johnny Depp. Only he doesn't just handle it. https://youtu.be/-X3hdFWmerQ?t=75

Jeff Goldblum Piano.

Not enough to be “triple threats” (act/sing/dance) in show business, they were pretty good instrumentalists as well:

https://youtu.be/baHH2Kqz1SQ

https://youtu.be/7bYvZEpHEMA

And, of course, an Academy award nomination for “Best Actor” makes one a movie star by any standard. He was inarguably a star as an instrumentalist. Some might even argue, the best tenor saxophone player of all time:

https://youtu.be/gIYV5kIdK9Q

Taking the twist on the OP a bit further, star instrumentalists who could handle a little acting:

https://youtu.be/YtjzVThkiFs

It's an old trick to include famous actor for better commercial success. Johnny Depp plays scored few notes on the guitar pretty clean, but still think it's more for commercial success than for the benefit of the gig.

Johnny Depp has been playing guitar for years in different bands, don't know his skill level.

What about Bradley Cooper, real or movie musician?

I know that Colin Firth learned to play the guitar as a child, but later he was banned from this instrument. Instead, he was offered to learn how to play the euphonium - a bass musical wind instrument. Later he played in a rock band, but it's just not very clear on which instrument.

The Bacon brothers

Levon Helm was (he of course played Sissy Spacek’s father in Coal Miner’s daughter), Dwight Yoakam (Sling Blade), and Billy Bob Thornton is the drummer in a Pop/Rock group. Loudon Wainwright III has done some acting, as has Sting. Jeff Goldblum is a very accomplished pianist. And Jeff Bridges did a great job of playing a Country singer in Crazy Heart, and had a solo album a coupla years ago.