Sum 41 is a Canadian rock band from Ajax, Ontario. They formed in 1996 as a five-piece consisting of lead vocalist/rhythm guitarist Deryck Whibley, lead guitarist Dave Baksh, guitarist Tom Thacker, bassist Jason McCaslin and drummer Frank Zummo.

Though they were originally called Kaspir, the group members decided to change the band’s name for a Supernova show on September 28, 1996, which happened to be the 41st day of their summer vacation. It is also hypothesized by many fans that the band’s name comes from the fact that if you take the word “fuck” and add all its letters (“F” being the 6th letter of the alphabet, “U” being number 21, etc) you get 41.

The band released their debut record as Sum 41 called Half Hour of Power in 2000. They followed it with the breakout sophomore record All Killer No Filler in 2001 and it contained several charting songs such as “Fat Lip” and “In Too Deep.”

In 2002, the band released Does This Look Infected? which was also a commercial and critical success. The singles “The Hell Song” and “Still Waiting” drove the band to stardom, and with their 2004 record Chuck, they planted themselves as giants in the punk rock scene.

Though it was received with mixed reviews, their 2007 album Underclass Hero became the highest grossing album of the band to date. It was then followed by Screaming Bloody Murder in 2011, 13 Voices in 2016 and Order in Decline in 2019. While none of these albums have been able to reach the commercial success as their predecessors, they have nevertheless received praise from fans and critics alike.

In May 2023, the band announced their intention to disband.

Sum 41 occasionally played as an alter-ego 1980s heavy metal band called Pain for Pleasure during shows.