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

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) - Wild Horses (Susan Boyle) - The Climb (Joe McElderry) - Ambitions (Joe McElderry)

Xanadu (film)
Music from the Motion Picture (1980)
See also: Xanadu (musical), Olivia Newton-John, Cliff Richard & Electric Light Orchestra
Songs: Suddenly (Olivia Newton-John & Cliff Richard) - Dancin' (& Olivia Newton-John & The Tubes) - Xanadu (Olivia Newton-John & Electric Light Orchestra) - Magic (Olivia Newton-John) - I'm Alive (Electric Light Orchestra)

Charli XCX
Charlotte Aitchison
Songs: Guess (feat. Billie Eilish) - I Love It (& Icona Pop) - Von Dutch - Girl, So Confusing - Apple

Xscape
Songs: My Little Secret - Do You Want to - Understanding - Tonight - Keep On, Keepin' On (& MC Lyte)

XXXTentacion
Songs: Fuck Love (& Trippie Redd) - Hope - Sad! - Roll in Peace (& Kodak Black) - Again (& Noah Cyrus)