Sum 41 is a Canadian rock band from Ajax, Ontario. The band was formed in 1996 and currently consists of Deryck Whibley (lead vocals, guitars, keyboards), Dave Baksh (lead guitar, backing vocals), Jason McCaslin (bass, backing vocals), Tom Thacker (guitars, keyboards, backing vocals), and Frank Zummo (drums, occasional backing vocals).

In 1999, Sum 41 signed an international record deal with Island Records and released its first EP, Half Hour of Power, in 2000. The band released its debut album, All Killer No Filler, in 2001. The album achieved mainstream success with its first single, "Fat Lip", which reached number one on the Billboard Modern Rock Tracks chart and remains the band's most successful single to date. The album's next singles "In Too Deep" and "Motivation" also achieved commercial success. All Killer No Filler was certified platinum in both the United States and the United Kingdom and triple platinum in Canada. 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" both charted highly on the modern rock charts.

The band released its next album, Chuck, in 2004, led by singles "We're All to Blame" and "Pieces". The album proved successful, peaking at number 10 on the Billboard 200. In 2007, the band released Underclass Hero, which was met with a mixed reception, but became the band's highest-charting album to date. It was also the band's last album on Aquarius Records. The band released the album Screaming Bloody Murder, on Island Records in 2011 to a generally positive reception, though it fell short of its predecessors' commercial success. The band's sixth studio album, 13 Voices was released in 2016, through Hopeless Records. IMPALA awarded the album with a double gold award for 150,000 sold copies across Europe. The band's seventh studio album Order in Decline was released on July 19, 2019. It was the band's last album on Hopeless Records. The band's eighth studio album, Heaven :x: Hell, was released on March 29, 2024, through Rise Records. In May 2023, the band announced that the album would be their last as they would be disbanding after its release and a worldwide headlining tour.

The band often performed more than 100 times each year and holds long global tours, most of which lasted more than a year. The group was nominated for seven Juno Awards and won twice – Group of the Year in 2003, and Rock Album of the Year for Chuck in 2005. Sum 41 was nominated for a Grammy Award for Best Hard Rock/Metal Performance for the song "Blood in My Eyes". From their formation to 2016, Sum 41 were the 31st best-selling Canadian artist in Canada.