"Locomotive (Complicity)" is an extended hard rock composition co-written by Slash and Axl Rose for Guns N' Roses, recorded for the band's 1991 album Use Your Illusion II. Clocking in at nearly nine minutes, the piece is built on aggressive, machine-like guitar riffs and funk-metal grooves that create a sense of relentless forward momentum, living up to its locomotive namesake. Slash and Duff McKagan developed the music at a rented Hollywood Hills house with early input from Izzy Stradlin, crafting a multi-part structure that shifts between sinewy, riff-driven verses and explosive choruses. Rose added lyrics addressing a volatile relationship with remorseful, vitriolic imagery, reportedly finding the song's musical complexity so challenging that he called the band's manager to vent his frustration. The composition features dynamic shifts across its length, fusing hard rock with funk-metal elements and building to a haunting piano-driven coda that provides emotional contrast to the earlier aggression. Rose's vocal performance ranges from cynical snarls to layered crooning, while Slash contributes multiple guitar solos throughout the extended arrangement. The song exemplifies the band's evolution toward longer, more technically ambitious compositions during the Use Your Illusion era. After going unplayed live for over two decades, it was revived during the Not In This Lifetime reunion tour beginning in 2016.
