Also known as the comic relief or the Funny Guy. A character whose primary role in the show is to relieve tension with oddball and/or hysterical antics. He has a job to do, but doesn't get into the thick of things and can stay somewhat detached. Since their purpose is to relieve tension, they almost always have immunity to dying when compared to the other characters. A guaranteed sign that the series is suffering from Cerebus Syndrome or that things are just going to go to Hell from here is to see whether this character either dies or has a complete and utter meltdown, no matter how deserved.
The term comes from Sam Rockwell's "Guy Fleegman" character in the movie Galaxy Quest (who, in a non-genreblind example of Lampshade Hanging, is afraid that he is only a Red Shirt, until another character ("Fred Kwan") suggests that maybe he is instead the "plucky comic relief"), which of course was spoofing the television show Star Trek.
In some cases, similar to Stupid Boss. Many sidekicks fit this description as well. Also see Amusing Alien, for otherworldly characters whose only purpose is comedy. Finally See The Face, where they have a purprose greater than comedy.
Reggie Mantle, the most comedic and magnificent jock in Riverdale.
Mukrezar is a soulless, murderous bastard. He completely wiped out all life on a continent, is an unrepentant torturer who apparently finds screams of the tormented 'soothing', and is also a terrible cook. Despite this, he is an amazingly quirky and charismatic leader, and usually gets an 'episode' every other chapter or so. As the humorous element.
Axel fills this role in Keyblade Masters, even though he's introduced late in the story. He also performs this duty in the sequel series, Sentinels of Chaos.
Frozen: Olaf and Sven. Olaf is the more prominent of the two, although he adds some quite heartfelt and "deep" moments to the movie. Sven's facial emotions are quite hilarious, but his few lines voiced by Kristoff provoke laughs.
Shrek: Donkey is a parody of the Plucky Comic Relief — when he isn't being a straight example.
As serious as The Secret of NIMH was in tone, there was a certain crow that happens to be the comic relief. And that crow in particular is Jeremy.
Humphrey from Alpha and Omega serves as the snappy one-liner of the movie. he is usually seen hanging out with his other omega buddies and is shown to try to cheer up an alpha named Kate, whom he likes to be with.
Justified in that this is stated to be the role of the Omegas in the pack; to break up fights and keep everyone's spirits up.
Guy in Galaxy Quest fears for the entire film that he is destined to die, as his character on the show, Crewman #6, was a typical Red Shirt that died in the first act of his only episode. Fred eventually calms his fear by suggesting Guy is actually this trope.
Fred himself also qualifies by spending most of the film oblivious to, or at least unreasonably calm about, the ostensible dangers they're going through. The original cut depicted him as a stoner, but this element was downplayed to receive a family-friendly rating. The remaining hints are enough to act as a Parental Bonus.
Aside from being The Lancer to Tom Cody'sThe Hero, Billy Fish filled this role for the scene where he refuses to give Ben Gunn the money. Tom manages to convince Billy, which follows with the latter complaining under his breath. And should we mention that Billy is played by Rick Moranis, an actual comedian?
The Largo brothers, Pavi and Luigi, fill this role in Repo! The Genetic Opera. In a movie like Repo, the comic relief duo is made up of a murderer and a rapist...
The MS T3k-subject Attack of the The Eye Creatures has the Peeping Tom Air Force guys, who manage to both avoid having any plot relevance or give their actions any actual humor or other, non-repulsive qualities.
Tuco from The Good, the Bad and the Ugly might qualify, given that most, if not all of the humorous moments in the film involve him in one form or another.
Bluebell, the comedian rabbit of Watership Down, serves as a comic relief not only to the readers, but also is an in-story tension breaker. Keehar the seagull serves the purpose in the film adaptation.
Madame Khokhlakov's role in The Brothers Karamazov is to provide lighthearted, trivial discussion versus everything else that goes on in the story. She is eternally cheerful and will talk you to death. Dostoevsky used her to insult his critics at the time by having her agree with their works.
Fred and George. As the series gets Darker and Edgier, one loses an ear and the other dies.
Ron Weasley also fills this role within the main trio, and he's an even earlier gauge of the series' impending dark turn: as early as book four, his general status as Chew Toy produces some moments of unexpectedly bitter resentment. By book seven, he's primed for a complete meltdown.
A casual reading of the Witches novels would suggest that Nanny Ogg's job is to keep bringing the funny, while Granny Weatherwax and Magrat get all the Crowning Moments Of Awesome. And this is the case, but what's not always apparent is that this is exactly how she likes things, and if she wanted to be Granny, she easily could be.
In Magic: The Gathering, Squee from the Weatherlight Saga. For example, the flavor text for Fool's Tome. More generally, goblins typically fill such a role. There was a Running Gag where goblins that could destroy things had a profession related to whatever it was they were destroying - Goblin Gardener destroyed lands, Goblin Medic dealt damage to creatures, and so on.
Launcelot Gobbo in The Merchant of Venice, who was written in specifically as this. His life offstage is referred to (he's got a family and a mistress), but onstage he's mostly there to give overdramatic monologues, spew Incredibly Lame Puns and complain about how converting Jews to Christianity will raise the price of pork. Gratiano qualifies, too.
Portal 2 subverts this with Wheatley, a moronic personality core who escorts the player through the early areas of the game and, with your help, attempts to engineer a coup against GLaDOS. The subversion comes when Wheatley, upon successfully replacing GLaDOS in the Enrichment Center mainframe, goes into full A God Am I mode and becomes the Big Bad of the game. Portal 2 has fairly equal distribution of comedy, but Portal 1 arguably has GLaDOS carrying all the comic responsibility. However, this can probably be excused as she is the only speaking character.
Joker from Mass Effect takes the role first as a Disabled Snarker but eventually becomes a straight example as he loosens up around the crew and learns he does not have to constantly prove himself like he did in flight school because of his disease. He becomes a Plucky Comic Relief character almost exclusively with only occasional moments of snarkiness by the second game.
The janitor from the Carol Reed Mysteries. Most of the time he isn't connected to the cases, he's mainly there to make the player laugh every once in a while.
Siegmeyer from Dark Souls, a bumbling knight who became Undead and ventured to Lordran for one last adventure. The player runs into him in various situations, where he's nearly always in quite a pickle.
A lot of them in the Whateley Universe. The junior high mages known as 'the three little witches', Go-Go (a speedster who used to go by 'Quickie' until she found out why everyone was laughing), Generator. Oh God, Generator. Wacky comic relief in other people's stories, horrifyingly effective hero in her own stories. There are school armbands that identify the pacifists (who won't fight back if they're bullied so you're supposed to leave them alone) and the Ultraviolents (Exactly What It Says on the Tin). Only Generator wears both. Not at the same time; that would be silly. She flips a coin every morning.
Jaune Arc of RWBY seems like he will become this, due to his air sickness in "Ruby Rose" and being launched before he can finish asking questions in "The First Step".
Later deconstructed, when Jaune rages at someone offering to help train him that he is sick of being the 'loveable idiot' and needs to be able to succeed on his own.
In the classic Warner Bros. cartoon Drip-Along Daffy, Daffy Duck is the supposed western hero, while Porky Pig is explicitly called the "comedy relief", dressed in a Gabby-Hayes sidekick outfit. Porky is 500 times more competent than Daffy, and ends up defeating the villain and being appointed sheriff.
Porky's character from Daffy's Duck Dodgers cartoon and series, Eager Young Space Cadet, is also supposed to be this.
Parodied in Titan Maximum, where it's stated that each military squad are required to consist of one of these. The one shown is woefully aware that he's unfunny since he originally just wanted a desk job.