Any instance where at least one other character is hanging around a couple and some form of social awkwardness results. They can either be:
A) a nuisance to the couple which gets told to them leave them alone frequently,
B) a character who doesn't want to spend time with the couple, which drags them along anyway, or
C) a character who is pulled into being with a couple due to circumstance and no parties necessarily have ill will toward each other, but awkwardness may ensue anyway.
Usually does not translate into a relationship between a couple and a third party who genuinely like to spend time together in a friendly way, since that would imply little to no awkwardness.
- There's a Type A example in the Boys' Love manga Challengers. The foreign transfer student Rick quickly becomes a nuisance after he starts following the main couple around in the hope of getting with Uke and Horrible Judge of Character Tomoe before Kurokawa, who has more morals when it comes to relationships, upgrades their relationship from Just Friends to Official Couple. Even after they become lovers he still hangs around with them just in case.
- A type C occurs in Ao Haru Ride with Touma, Uchimiya, and Shun, except for the fact that Touma and Uchimiya are the ones with girlfriends. Therefore, whenever the three run into Futaba and her friends, Touma and Uchimiya end up making plans with their girlfriends and leaving out Shun.
- Minami in The Irregular at Magic High School is a type C. It's her job to guard Miyuki, even when the latter is cuddling with her fiance.
- Robin: While Ives prefers to only join Tim and Ariana if its a double date and he's accompanied by Callie things don't always work out in his favor and he usually antagonizes Ari even if he is with Callie. Unknown to Tim Ives is actually an incredibly useful third wheel because whenever Tim takes off to deal with something as Robin without an explanation he Ives makes one up for him while also implying Ari is being ridiculous for questioning her boyfriend's disappearance.
- Ultimate Daredevil & Elektra: Elektra and Matt have met, and fell in love. And Foggy? Is there anything he can do to help Matt? Yes: he can help by leaving.
- Timon and Pumbaa of The Lion King certainly become third wheels once Simba and Nala meet up again. It definitely is mostly type C, but Simba kind of politely lets Timon know that the two of them aren't wanted, making it somewhat type A.
- In The Adventures of Milo and Otis, main characters Milo the cat and Otis the dog spend most of the film trying to reunite, but when Milo falls in love with another cat, Otis becomes this for a little while. Otis is mostly a case of type C.
- Both Sherlock Holmes (2009) and its sequel Sherlock Holmes: A Game of Shadows are ripe with this trope. Holmes is a third wheel to Watson and Mary, or Mary is a third wheel to Holmes and Watson; Heterosexual Life-Partners or Ho Yay, your choice.
- At the end of Kick-Ass, Todd is stuck reading a comic book between his previously nerdy friends who are now happily snogging the girlfriends they acquired in the course of the movie.
- In What Price Hollywood?, Max becomes this much to Mary and Lonnies annoyance. In one instance, he comes to their house flat-out drunk and says hell burn their house down if they dont let him in. They let him in, and he goes into their bedroom, completely unaware of how hes driving a serious wedge between Mary and Lonnie.
- Harry Potter:
- When considering the idea of his two best friends getting together, one of Harry's concerns is that it'll be impossible for the three of them to hang out like they used to. Luckily, they spend too much time snarking at each other to turn into Sickeningly Sweethearts.
- While staying at Grimmauld Place in the seventh book, Harry notices Ron and Hermione fell asleep together holding hands, which does make him feel rather lonely.
- Mansfield Park: Type C: Henry Crawford visits Fanny Price in Portsmouth and tries to get her on her own, but finds Fanny's 15-year-old sister Susan a hindrance.
- The Heroes of Olympus: Type C: Leo Valdez, first with his two best friends Jason and Piper after they start dating. Now he's the seventh wheel since all of his other friends have started dating each other. The villain mocks him for never fitting in.
- A Mr. Show sketch is about this: a couple's friend joins them on their honeymoon. The wife is type A but the husband is type C. Said third wheel breaks into a song about this every time the words "third wheel" is said.
- In the Star Trek: The Next Generation episode, "Manhunt", Troi's mother, Lwaxana, tries to trick Captain Picard into spending a romantic dinner alone with her. Picard, seeing through her motives, asks Lt. Commander Data to join them. Data spends the entire meal giving long, detailed lectures on his work.
Picard: Data, you will never know how much I owe you for that.
Data: Indeed, Captain? I know many more interesting anecdotes, sir. For example...
Data: Yes, sir.
- On How I Met Your Mother, Ted Mosby, when between relationships, was usually C, but sometimes could be A or C to Marshall and Lily. When he very briefly moved out, they realized how much they needed him since he was the one who bought most of the household items like towels, dishes, food,...
- Once one of the guys starts dating on The Big Bang Theory, at least one of the others becomes this for the couple:
- When Leonard and Penny first got together and before Sheldon was introduced to Amy (and frankly, even after), he became their third wheel. Less awkward, more annoying the heck out of them with Sheldon being generally oblivious to it. To the point that Sheldon's neediness has even prevented Leonard and Penny from moving in with one another full-time now that they've married.
- Then when Howard started dating Bernadette, it was Raj's turn. Unlike Leonard, Penny, and Sheldon, this one ended up playing both ways because of Howard and Raj's considerable Ho Yay, with Bernie and Raj taking turns as the third wheel.
- With Raj finding his own relationship, Stuart has taken over. He's been living with Howard and Bernadette after first the comic book store burning down, and then the death of Mrs. Wolowitz (with whom he had been staying while getting back on his feet). Stuart is perfectly happy with the arrangement, however, and all the discomfort is on Howard and Bernadette's end, with neither quite bringing themselves to issue an ultimatum for him to move back out.
- The Affair: Max indicates that he's always felt this way towards Noah and Helen, valuing his friendship with the former but having an unrequited crush on the latter. He actually supports Noah financially after their separation just so he can have a shot at Helen again. Noah later calls him out on this when he realizes his "friend"'s real motive.
- On The Cosby Show, Rudy's best friend Kevin becomes this when she starts dating a boy. Rudy doesn't see a problem with it, but the boy straight out calls Kevin a third wheel at one point.
- On Schitt's Creek Stevie is shown to be this to David and Patrick a few times. Alexis is also seen hanging out with David and Patrick. Later, Stevie drags David along as she pursues Emir, even though she knows David wouldn't want to be the third wheel.
- The Strange Calls: Banks is all set to go on a date with his love interest, Kath, but the date is crashed by his boss, who also has an interest in her. Awkwardness ensues.
- In the novelty song "Third Wheel" by comedian Tim Hawkins, the narrator is a type A third wheel (watch it here).
- Robert from Company willingly plays third wheel to five married couples he's friends with. In fact, they love and depend on him so much they have several songs about him third wheeling.
What would we do without you?How would we ever get through?Should there be a marital squabbleAvailable Bob'llBe there with the glue
- In the Friendship is Magic fan game, Super Lesbian Horse RPG, Rainbow Dash complains that Twilight would be this on her date with Fluttershy. Twilight's Joined Your Party text even calls her this. This becomes a Brick Joke later in the game when Applejack joins the party. She's dubbed the fourth wheel, upgrading the party to "car" status.
- In The Quick and Dirty Life of Fritz Fargo, Fritz's best friend Eddie brings him along on a date.
- Sleepless Domain: When the Fire/Ice Duo Undine considers joining forces with turns out to be a Sickeningly Sweethearts Battle Couple, she gets the mental image of a burning wheel, a frozen wheel and a wheel engulfed in water (representing her own Making a Splash powers). The burning and frozen wheels have a heart between them.
- In "Dan Vs. The Fancy Restaurant" Dan accompanies Chris and Elise on their anniversary dinner.
Dan: Why is having a third wheel a bad thing? Third wheels provide stability, that's just physics.
- In the Futurama episode, "Put Your Head on my Shoulders" Fry starts to worry that his relationship with Amy is going too fast, so he intentionally invites a third wheel on their date.
Amy: So, ready for a secluded picnic with just you and me?
Fry: Hey, you know who loves secluded picnics with just you and me? (looks over at Leela who shakes her head.) Uh, Dr. Zoidberg.
Zoidberg: Did someone say something about a free hot meal?
- The Mickey Mouse short, "Third Wheel" has Goofy inviting himself on Mickey and Minnie's date.
- In the earlier House of Mouse short "Daisy's Road Trip", Daisy invites herself on Mickey and Minnie's road trip to watch the sunset.
- A non-romantic variation appears in the Kim Possible episode "Two to Tutor". Señor Senior Senior hires Shego to tutor Junior in proper villainy, but becomes increasingly resentful as Shego brusquely brushes off his attempts to drop in on the lessons and see how Junior is doing. Finally, he goes so far as to tip off the intended target of their planned robbery.
- Cyborg deliberately becomes one of these in the Teen Titans Go! episode "Rocks and Water".
- Mentioned in an episode of Phineas and Ferb, with Stacy being the third wheel to Candace and Jeremy.
Stacy: Lately I've been feeling like a third wheel around you guys.Candace: What? No. I always saw it more like Jeremy and I were two wheels and you were separate, on a unicycle all (sings a quick snipet of "Entrance of the Gladiators").
- The Transformers: Prime episode "Metal Attraction" has a non-romantic version. Jack's mom has recently been let in on the masquerade, and her sudden interest in everything is starting to grate on Arcee. Then Bulkhead's human partner tags along on one of their missions, and they start jamming to rock music together.
Arcee: No matter where I turn, I'm the third wheel.
- At the end of the Life With Loopy episode "Larry's Girl", Loopy ends up never leaving Larry and Stacey alone once they become a couple.
- DuckTales (2017): In the episode "The Golden Lagoon of White Agony Plains!", Flintheart Glomgold accompanies Scrooge and Goldie (who have Belligerent Sexual Tension) on their quest to find the Golden Lagoon. The delusional narcissist Glomgold is, he believes Goldie is in love with him, and he mockingly calls Scrooge a third weel.