X Ambassadors
Songs: Happy People (& Teddy Swims & Jac Ross) - Sucker for Pain - Unsteady - Blinding Lights - Renegades

X Factor
Joe McElderry, Leon Jackson, Same Difference, The X Factor Finalists, Alexandra Burke, Steve Brookstein, Shayne Ward, Leona Lewis, Susan Boyle, Jedward, Maria Lawson & Cher Lloyd
Songs: Hallelujah (Alexandra Burke) - A Moment Like This (Leona Lewis) - Summertime (Leona Lewis live) - The Climb (Joe McElderry) - Wild Horses (Susan Boyle)

Xanadu (film)
Music from the Motion Picture (1980)
See also: Xanadu (musical), Olivia Newton-John, Cliff Richard & Electric Light Orchestra
Songs: Don't Walk Away (Electric Light Orchestra) - Whenever You're Away from Me - Xanadu (Olivia Newton-John & Electric Light Orchestra) - Magic (Olivia Newton-John) - All Over the World (Electric Light Orchestra)

Xavi
Also known as Joshua Xavier Gutierrez Alonso
Songs: La diabla

Charli XCX
Charlotte Aitchison
Songs: I Love It (& Icona Pop) - Fancy (& Iggy Azalea) - Speed Drive (Barbie (2023 film)) - Vroom Vroom - 1999 (& Troye Sivan)

Xscape
Songs: Just Kickin' It - My Little Secret - Understanding - Who Can I Run to - Keep On, Keepin' On (& MC Lyte)

XXXTentacion
Songs: Changes - Hope - Moonlight - Look at Me! - Sad!