Primus is an American rock band formed in El Sobrante, California in 1984. The band is currently composed of bassist/vocalist Les Claypool and guitarist Larry "Ler" LaLonde. Primus originally formed in 1984 with Claypool and guitarist Todd Huth, later joined by drummer Jay Lane, though the latter two had departed the band by the beginning of 1989, and were replaced by LaLonde and Tim "Herb" Alexander respectively.

The "classic" lineup of Claypool, LaLonde and Alexander debuted with the live album Suck on This, which was self-released in 1989 on Claypool's label Prawn Song and reissued a year later by Caroline Records. Caroline also released Primus' debut studio album Frizzle Fry (1990), which was critically well received, and its underground success led to interest from major record labels. Their second studio album and major-label debut Sailing the Seas of Cheese (1991), released through Interscope Records, launched the band into mainstream exposure, supported by their first charting single "Jerry Was a Race Car Driver" and receiving platinum certification within a decade after its release. Primus repeated its success with their next two albums, Pork Soda (1993) and Tales from the Punchbowl (1995), both charting in the top ten on the Billboard 200, and being certified platinum and gold respectively by the RIAA. Pork Soda featured the band's top ten hit on the Billboard rock chart, "My Name Is Mud", while Tales from the Punchbowl's lead single "Wynona's Big Brown Beaver" has the distinction of being their only song to chart anywhere outside of North America.

Alexander left the band in 1996 and was replaced by Bryan "Brain" Mantia, with whom Primus recorded two more studio albums – Brown Album (1997) and Antipop (1999) – as well as the covers EP Rhinoplasty (1998) and the original theme song for the TV show South Park. The band went on hiatus in 2000 but resumed activity in 2003, reuniting with Alexander for the EP/DVD Animals Should Not Try to Act Like People and touring sporadically throughout the 2000s before Alexander once again left in 2010. Lane rejoined the band and appeared on their seventh studio album – and first in twelve years – Green Naugahyde (2011). Following Lane's departure in 2013, Alexander returned to the band once again and Primus would record two more albums with him – Primus & the Chocolate Factory with the Fungi Ensemble (2014) and The Desaturating Seven (2017) – as well as the EP Conspiranoid (2022). Alexander announced his third departure from the band in October 2024.

Primus is characterized by its irreverent, quirky approach to music distinguished by Claypool's bass-centric songwriting and eccentric lyrical themes. The band's musical style, which draws influences from progressive rock, metal, funk, and psychedelic music, has been noted as difficult to categorize and is most frequently described by critics as funk metal, a label the band has rejected. In 1993, Robert Christgau remarked: "[Primus is] quite possibly the strangest top-10 band ever, and good for them."