Guest appearances
In addition to appearing on Slayer's albums, he has also made several guest appearances for other artists. While lending production to 1986's Reign in Blood, Rick Rubin was also helping with the production of the Beastie Boys' debut album Licensed to Ill. Rubin felt the track "No Sleep till Brooklyn" needed a guitar solo, so he called in King to lay down the part. King has since commented that his playing ability "certainly wasn't that of a virtuoso". The video for "No Sleep till Brooklyn", whose title was a spoof on Motörhead's 1981 live album No Sleep 'til Hammersmith, was originally intended to feature King being knocked offstage by a gorilla, but King refused. King replied, "If there's gonna be anyone knocking anyone offstage, it'll be me knocking the gorilla", which was what subsequently happened.
On Licensed to Ill, King also played the guitar solo on the song "(You Gotta) Fight for Your Right (To Party!)".
King contributed the main lead guitar solo and outro part to Pantera's song "Goddamn Electric", which appeared on the 2000 album, Reinventing the Steel. King's rig was set up in Pantera's bathroom backstage just after Ozzfest 1999 in Dallas, as the group still did not have their own dressing room, on top of not appearing on the festival bill.
King has also made several guest appearances on Marilyn Manson's Rape of the World Tour, joining the band to play tracks such as "Little Horn", "1996" and "Irresponsible Hate Anthem". Many fans noticed elements of King's own style used on these occasions.
He also appeared on an episode of Daniel Tosh's television series Tosh.0, alongside Corey Taylor of Slipknot. Both playing themselves as audience members.
On October 21, 2010, the final date of the Jägermeister Music Tour, King joined Megadeth on stage at the Gibson Amphitheater in Hollywood to perform "Rattlehead" which was the first time in 26 years that King had shared the stage with Megadeth (King had been a touring substitute for a few months in 1984).
King contributed a guitar solo on the title track for the 2010 album Witchkrieg by the Swedish blackened thrash band Witchery. He also appears in the music video playing his solo.
He made an appearance in the 2009 movie Brooklyn's Finest as a member of SWAT team led by Ethan Hawke's character. In 2022, he appeared in the comedy horror film Studio 666 as Krug.
In January 2025, King played on the theme song to professional wrestler Damian Priest. On April 20, 2025, King performed Priest's theme song live at WrestleMania 41.