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

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) - Somewhere Over The Rainbow (Shayne Ward) - Summertime (Leona Lewis live)

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

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

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

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