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

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) - Somewhere Over The Rainbow (Shayne Ward) - Summertime (Leona Lewis live) - Against All Odds (Steve Brookstein)

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) - Suspended in Time - Magic (Olivia Newton-John) - Suddenly (Olivia Newton-John & Cliff Richard) - All Over the World (Electric Light Orchestra)

Charli XCX
Charlotte Aitchison
Songs: party 4 u - Von Dutch - I Love It (& Icona Pop) - New Shapes (& Christine and the Queens & Caroline Polachek) - Vroom Vroom

XXXTentacion
Songs: Fuck Love (& Trippie Redd) - Changes - Moonlight - Again (& Noah Cyrus) - Hope