Sum 41 is a pop punk rock band from Ontario, Canada, formed in 1996 by vocalist/guitarist Derryck Whibley and drummer Steve Jocz. They were soon joined by lead guitarist Dave Baksh and after a set of bass guitarist they finally settled on Jason "Cone" [=McCaslin=] in 1999. Their first album (''All Killer, No Filler'') was released in 2001 and spawned their most successful single, "Fat Lip".

Their follow-up album ''Does This Look Infected?'' was released in 2002. It featured a darker sound and also more serious lyrical themes. This continued onto their third album ''Chuck'', released in 2004. In 2006, Baksh left the band to focus on his own band Brown Brigade. He was replaced by Tom Thacker, who was initially only a live member, while their 2007 album ''Underclass Hero'' was recorded as a trio. Thacker became an official member in 2009 and helped to co-write title track for their fifth studio album ''Screaming Bloody Murder'', released in 2011. However, that album (along with ''Underclass Hero'') had all guitar parts performed by Whibley.

The bandís music is primarily pop punk and punk rock, though they have diversified over the years. They moved from pop punk (with some rap rock) on ''All Killer, No Filler'', to melodic hardcore on ''Does This Look Infected?'' and ''Chuck'' (with the latter having alternative metal influences and lighter alternative rock), back to pop punk with ''Underclass Hero'', and back to melodic hardcore with ''Screaming Bloody Murder''.

Sum 41 currently consists of Whibley on vocals and rhythm guitar, Tom Thacker on lead guitar and backing vocals and Cone on bass and backing vocals. Drummer Steve Jocz left the band in April of 2013, leaving Derryck as the sole remaining founding member. Jocz replacement has not been announced yet.

* "Half Hour of Power" (2000, EP)
* "All Killer, No Filler" (2001)
* "Does This Look Infected?" (2002)
* "Chuck" (2004)
* [[LiveAlbum "Go Chuck Yourself"]] (2005, released in Japan as Happy Live Surprise)
* "Underclass Hero" (2007)
* [[GreatestHitsAlbum "All the Good Shit"]] (2008)
* "Screaming Bloody Murder" (2011)

!They provide examples of the following tropes:
* TheAlcoholic: Deryck admitted, that he used to drink very excessively. He eventually stopped after he collapsed and doctors told him, that if he had one more drink, he would probably die.
* AllDrummersAreAnimals: Steve.
* AlterEgoActing: As Pain for Pleasure (see below). Also in music video for Still Waiting, they performed as The Sums and were renamed. Derryck was Sven, Dave was Holmes, Steve was Sergio and Cone was Thurston.
* AscendedExtra: Tom, as of 2009.
* CallBack: Bridge to the song Subject to Change (found on japanese version of Chuck) is the same as at the end of No Reason (another, earlier song from the same album). And of course, chorus of the former song was later re-used as chorus to Underclass Hero.
* CerebusSyndrome: ''Half Hour of Power'' and ''All Killer, No Filler'' were both very upbeat, MTV-friendly pop-punk albums. They were followed by the [[NewSoundAlbum hardcore/horror punk inspired]] ''Does This Look Infected?'' and, after that, the very sombre ''Chuck'' and equally so ''Screaming Bloody Murder'', making the much lighter ''Underclass Hero'' a BreatherEpisode.
* CountryMatters: A.N.I.C., which stands for Anna Nicole Is (a) Cunt.
** Concerts [[CrossesTheLineTwice take this a step further]] with Derryck introducing the song as "Anna Nicole Is A Fucking Stupid Cunt!"
* DarkerAndEdgier: Does This Look Infected? was this to All Killer, No Filler and Chuck was this to Does This Look Infected and finally Screaming Bloody Murder is this to Underclass Hero.
* DisproportionateRetribution: In Basketball Butcher, Stevo murders (and later [[ImAHumanitarian cooks and eats]]) Cone simply because he beat him in a basketball match.
* ExactlyWhatItSaysOnTheTin: Half Hour of Power, although it's actually slightly shorter, with the 30 minutes length being only done with added silence after the last song.
* GenreShift / NewSoundAlbum: See above.
* HeavyMetal: They had an AlterEgoActing band named [[FakeBand Pain for Pleasure]], where they performed in wigs and costumes and used nicknames - Steve (who was lead vocalist here) was Pain, Derryck (drummer) was Gunner, Dave was Pleasure and Cone was Sniper. They recorded three songs under this monicker: Pain for Pleasure, Reign in Pain and WWVII Parts 1 & 2. They also appeared as this in two of their music videos: Fat Lip (where they performed their self-titled song) and We're All to Blame (where they were announced as next band to perform on Solid Gold). Incidentally, Derryck is shown as guitarist in both of those appearances, although he actually played drums in this band.
* ImAHumanitarian: In one of their web videos, Basketball Butcher, after losing against Cone in basketball match, Steve kills him and then cooks him. Later, Derryck and Dave come in. They ask him what is for the dinner. Steve replies with "You!".
* InsultBackfire: [[Music/{{Oasis}} Noel Gallagher]] once called them "the worst band in the world". They liked it enough to use it as a slogan for a while.
* LighterAndSofter: While darker than All Killer No Filler, Underclass Hero was this to the album previous album Chuck and sounds closer to Does This Look Infected.
* MoodWhiplash: ''Chuck'' is especially made of this. Not only does it put relatively softer songs ("Some Say", "Pieces" and "Slipping Away") between fast and aggresive songs, but even some of the heavier songs on the album have slower, melodic parts such as on "We're All to Blame" (aggresive verses, calm choruses) or "88" (which has calmer first verse and the outro, but is otherwise fast and heavy).
* NonAppearingTitle: Sorted by albums, excluding some partial examples and istrumentals.
** ''Half Hour of Power'': "Machine Gun", "Summer" (also on ''All Killer, No Filler''), "Second Chance for Max Headroom" and "Dave's Possessed Hair".
** ''All Killer No Filler'': "Introduction to Destruction", "Fat Lip", "Crazy Amanda Bunkface" and "Heart Attack".
** ''Does This Look Infected?'': "The Hell Song", "A.N.I.C.", "No Brains", "Mr. Amsterdam", "Hyper-Insomnia-Para-Condriod", "Billy Spleen" and "Hooch",
** ''Chuck'': "Angels with Dirty Faces", "Welcome to Hell", "88", "Moron", "Noots" and "Subject to Change".
** ''Underclass Hero'': "Underclass Hero", "Speak of the Devil", "With Me", and "Confusion and Frustration in Modern Times".
** ''Screaming Bloody Murder'': "Screaming Bloody Murder", "Jessica Kill", "Crash" and "Exit Song",
* PunkRock
* RapRock: "Fat Lip" and "What We're All About".
* RockTrio: During Underclass Hero era they officially consisted only of Derryck, Cone and Steve (Tom was a live member only and as such did not play on the album, nor did he appear in music videos). Screaming Bloody Murder was also recorded in three piece despite Tom Thacker already being a member of the band at that point (he did get a co-writing credit for title track, though).
* SpecialGuest: [[Music/{{Slayer}} Kerry King]] on [[Film/SpiderMan What We're All About]].
** Sum 41 themselves performed on Little Know It All by [[Music/TheStooges Iggy Pop]] and Get Back by Ludacris.
* StartMyOwn: Dave Baksh, who left to form Brown Brigade.
* StepUpToTheMicrophone: Aside from singing on Pain for Pleasure songs, Steve also rapped on Fat Lip, What We're All About and Thanks for Nothing (along with Derryck and in case of first two, Dave).
* TheSomethingSong: The Hell Song, Exit Song
* TitleTrack: ''Underclass Hero'' and ''Screaming Bloody Murder''.
* TrashTheSet: The end of Still Waiting video. Also in Walking Disaster.
* WarIsHell: Still Waiting..
** ''Does This Look Infected?'':