Justin Chancellor was born on November 19, 1971. The English bassist joined Tool in 1995 and helped make the bass a lead voice in songs such as “Schism,” from 2001’s Lateralus. Its opening figure is a useful introduction to his role: a distinct musical idea around which the rest of the band can build.
His first instrument was a guitar. In Ernie Ball’s 2016 String Theory interview, Chancellor recalled taking a school guitar class at seven, learning a C chord and receiving a guitar for his eighth birthday. He’d already been listening closely to his parents’ small collection of records, playing them after school and studying their covers. Making those sounds himself gave that fascination somewhere to go.
Playing in the British band Peach brought him into contact with Tool through shared European tour dates. When the invitation to audition arrived in 1995, though, he nearly passed. “I actually said no because I was terrified,” he told Revolver in 2019. His brother pushed him to reconsider, and Chancellor called back to ask for the chance. He got the position and made his Tool album debut on Ænima in 1996.
Finding the right instrument was part of finding his place in the band. During the Ænima sessions, Chancellor borrowed a friend’s Wal bass that had been converted from fretless to fretted. He recalled in Premier Guitar’s 2024 Rig Rundown that its tone immediately suited Tool’s sound, prompting him to order his own version. That practical studio discovery became central to his approach: an instrument whose voice could hold its place alongside the guitar and drums.
Lateralus presented a different challenge. Four songs had already been written when Chancellor joined the work on Ænima; the follow-up required the musicians to develop an entire album together. In a retrospective published by Prog in 2023, he described working with guitarist Adam Jones and drummer Danny Carey to reshape his rhythmic ideas. They might simplify an awkward pattern into a straightforward pulse, find the song inside it, then rebuild its complexity. To keep track, they gave riffs names and mapped their order and beat counts on a whiteboard. Even “Schism” tested his confidence. Chancellor recalled doubting its suitability as a single because it sounded so unusual, while Jones and Carey heard its appeal immediately. The same bandmates who encouraged him to bring unfamiliar ideas into Tool could hear a direct connection with listeners in something he feared might be too strange.
That willingness to work an idea in both directions carried into Fear Inoculum, released in 2019. Discussing its title track with Bass Magazine, Chancellor explained that the more complicated second half came first. Jones suggested reworking those themes into a simpler 4/4 passage. The result let the song move from a more familiar rhythmic footing into the material that had originally sparked it.
The album also gave each member a chance to create an interlude, with production and mixing shared. For Chancellor’s “Mockingbeat,” he found a use for a Hamer 12-string bass whose sound had overwhelmed other parts during the sessions: reversing a recorded line made it the piece’s opening. He added an Arturia DrumBrute analog drum machine, bringing his interest in electronic music into the track that closes the digital edition of Fear Inoculum.
