King's X is an American rock band formed in Springfield, Missouri in 1979. They were first called the Edge and later became Sneak Preview before settling on their current name in 1985. The band's current lineup has remained intact for more than four decades, consisting of vocalist and bassist Doug Pinnick, drummer Jerry Gaskill and guitarist Ty Tabor. Their music combines progressive metal, funk and soul with vocal arrangements influenced by gospel, blues, and British Invasion rock groups. Despite a largely underground reputation as the "musician's musicians", King's X was pivotal in the early development of progressive metal, and produced a series of early records considered essential within the genre. The band's lyrics are largely based on the members' struggles with religion and self-acceptance. King's X was ranked No. 83 on VH1's 100 Greatest Artists of Hard Rock.

King's X has released thirteen studio albums, two official live albums, and several independent releases. After signing to both Atlantic and Megaforce Records in 1987, they broke into the mainstream with their first six albums, including their only top 100 charting albums Faith Hope Love (1990) and Dogman (1994). The band's most recent studio album, Three Sides of One, was released in 2022 on the InsideOut Music label. Since leaving Atlantic Records, following the release of Ear Candy in 1996, King's X has released albums through Metal Blade Records, InsideOut Music and independently, respectively. Each member of the group has recorded several solo albums and has made numerous guest appearances on other artists' albums, as well as participated in numerous compilation projects. Pinnick and Tabor also have many albums released with side bands in which they participate.

Throughout their career the band secured opening slots on arena tours, including opening for bands like Cheap Trick, Iron Maiden, AC/DC, Scorpions, Pearl Jam and Mötley Crüe as well as the Woodstock '94 festival. They continue to tour and perform live.

The spiritual nature of the band's lyrics, particularly on their first four albums, has often led to them being labeled a Christian rock band, a label that the members have rejected. King's X has also been cited as an influence or inspiration to numerous acts such as Pearl Jam, Alice in Chains, Soundgarden, The Smashing Pumpkins, Pantera, Dream Theater, Skillet, Devin Townsend and Soil.