X Ambassadors
Songs: Blinding Lights - Renegades - Unsteady - Boom - Ahead of Myself

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) - You'll Never Walk Alone (Ray Quinn) - Against All Odds (Steve Brookstein) - Heroes (The X Factor Finalists) - Somewhere Over The Rainbow (Shayne Ward)

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

Charli XCX
Charlotte Aitchison
Songs: party 4 u - I Love It (& Icona Pop) - Yuck - Von Dutch - The Girl, So Confusing (version with Lorde)

Xscape
Songs: The Arms of the One Who Loves You - Keep On, Keepin' On (& MC Lyte) - Tonight - Understanding - Just Kickin' It

XXXTentacion
Songs: Fuck Love (& Trippie Redd) - Moonlight - Changes - Again (& Noah Cyrus) - Roll in Peace (& Kodak Black)