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

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) - Summertime (Leona Lewis live) - A Moment Like This (Leona Lewis) - You'll Never Walk Alone (Ray Quinn) - 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: All Over the World (Electric Light Orchestra) - Don't Walk Away (Electric Light Orchestra) - Whenever You're Away from Me - Xanadu (Olivia Newton-John & Electric Light Orchestra) - Suddenly (Olivia Newton-John & Cliff Richard)

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

Charli XCX
Charlotte Aitchison
Songs: I Love It (& Icona Pop) - Fancy (& Iggy Azalea) - 1999 (& Troye Sivan) - Boom Clap (The Fault In Our Stars) - Vroom Vroom

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

XXXTentacion
Songs: Roll in Peace (& Kodak Black) - Hope - Moonlight - Sad! - Changes