Pop/Rock/R&B:
* Harry Styles: (One Direction, solo career)
* Justin Timberlake: (NSYNC, solo career)
* Jared Leto: (30 Seconds to Mars)
* Joe Jonas: (Jonas Brothers, DNCE)
* Nick Jonas: (Jonas Brothers, solo career)
* Zac Efron: (High School Musical, solo career)
* Jamie Foxx: (Soul, Ray, solo career)
* John Legend: (Voice actor, Grammy winner)
* Will Smith: (Fresh Prince of Bel-Air, solo career)
* Mark Wahlberg: (Marky Mark and the Funky Bunch)
Musical Theatre:
* Hugh Jackman: (Les Misérables, The Greatest Showman, Wolverine)
* Lin-Manuel Miranda: (Hamilton, In the Heights, Moana)
* Jonathan Groff: (Hamilton, Frozen, Looking)
* Neil Patrick Harris: (How I Met Your Mother, Hedwig and the Angry Inch)
* Ben Platt: (Dear Evan Hansen, Pitch Perfect)
* Darren Criss: (Glee, American Crime Story, Hollywood)
* Leslie Odom Jr.: (Hamilton, One Night in Miami)
Country:
* Tim McGraw: (The Blind Side, Friday Night Lights)
* Brad Paisley: (Cars 3)
* Luke Bryan: (American Idol judge)
* Garth Brooks: (The Last Unicorn)
Other Genres:
* Keanu Reeves: (Bill & Ted's Excellent Adventure, The Matrix, Dogstar)
* Tom Hanks: (Big, Forrest Gump, You've Got Mail, Toy Story)
* Tom Cruise: (Top Gun, Mission: Impossible, Rock of Ages)
* Kevin Spacey: (House of Cards, The Usual Suspects)
* Chris Pratt: (Guardians of the Galaxy, Jurassic World, The Lego Movie)
This is just a small sample, as there are many other actors who have singing careers.
To explore further, you can use search engines like Google or IMDb to find more actors who are also singers.