Probot was a heavy metal side project of ex-Nirvana drummer and Foo Fighters rhythm guitarist and lead-singer Dave Grohl. An album was recorded out of the material and released in February 2004. It featured one single entitled "Centuries of Sin/The Emerald Law".

After years of popularity in the alternative rock scene, Dave Grohl wanted to express the passion for heavy metal he bore since his youth. In 2000, with some free time on his hands, Grohl recorded seven instrumentals without vocals but with various heavy metal musicians in mind (i.e. one song with the intense thrash style of Sepultura, another in the classic metal flavor of Motörhead). He labeled the recordings "Probot" but never had the intention of fully developing or releasing the material. Years later, with the help of friend Matt Sweeney, Grohl slowly managed to contact some of the artists in mind and began developing a studio album out of his work. He noted in a Rolling Stone article: "I came up with my wish list of all of my favorite singers from this era which is '82 to '89 underground metal, and all the bands I listened to at the time: Eric Wagner from Trouble and Snake from Voivod and Cronos [from Venom] and Lemmy and Wino. We started making phone calls trying to find all these people."

David Eric "Dave" Grohl (born January 14, 1969) is an American rock musician, multi-instrumentalist, and singer-songwriter, who is the lead vocalist, guitarist, primary songwriter and founder of the Foo Fighters, prior to which he was the drummer in the grunge band Nirvana. He is also the drummer and co-founder of the rock supergroup Them Crooked Vultures. Grohl has additionally written all the music and performed all the instruments for his short-lived side projects Late! and Probot, as well as being involved with Queens of the Stone Age numerous times throughout the past decade. He has performed session work (as a drummer) for a variety of musicians, including Garbage, Killing Joke, Nine Inch Nails, The Prodigy, Slash, Juliette Lewis, Tenacious D, Tom Petty and the Heartbreakers, and Lemmy Kilmister.

As a child, Grohl's family relocated from Warren, Ohio, to Springfield, Virginia, a suburb of Washington, D.C. Three years later, when Grohl was six, his parents divorced, and Grohl grew up living with his mother.

Thomas Jacob "Jack" Black (born August 28, 1969) is an American comedian, actor and musician. He makes up one half of the comedy and satirical rock duo Tenacious D. The group has three albums as well as a television series and a film. His acting career is extensive, starring primarily as bumbling, cocky, but internally self-conscious outsiders in comedy films. He was a member of the Frat Pack, a group of comedians who have appeared together in several Hollywood films, and has been nominated for a Golden Globe award. He has also won an MTV Movie Award, and a Nickelodeon Kids Choice Award as well as hosting the 2006, 2008, and 2011 Kids Choice Awards.

Black was born in Santa Monica, California, the son of two satellite engineers, Judith (née Cohen), who worked on the Hubble Space Telescope, and Thomas William Black. His mother is Jewish and his father converted to Judaism (Black attended Hebrew school). On The Tonight Show, he said his surname may have come from the occupational name Blacksmith. Black's parents divorced when he was 10; Black moved to Culver City with his father and frequently visited his mother’s home. As a child, Black appeared in a commercial for the Activision game Pitfall! in 1982, which was later shown during an appearance on Jimmy Kimmel Live and again on The Tonight Show with Conan O' Brien. When Black entered high school, his parents enrolled him at the Poseidon School, a private secondary school engineered specifically for students struggling in the traditional school system. Black also attended the Crossroads School, where he excelled in drama. He later attended UCLA but dropped out during his sophomore year to pursue a career in entertainment, at which point his father discontinued his financial support.^{[citation needed]} Fellow UCLA alumnus Tim Robbins later cast Black in Bob Roberts. He also had recurring roles on the HBO sketch comedy series Mr. Show.