30 Rock has a lot of characters like this, since a recurring theme of the show is how pathetic the cast secretly are:
Jenna is a neurotic and vicious Attention Whore who views herself as A-List material even though she's a horrible actress, barely capable of getting jobs outside of TGS because everyone is either terrified of working with her or think she sucks. Her main way of getting into the spotlight is throwing engineered fits and controversies so that tabloids acknowledge her.
Tracy Jordan, is more successful and well-known than Jenna, but is still B-List at best and is far stupider than he thinks he is. He's spoiled beyond belief so he essentially thinks that he's always in the right no matter how poorly he does.
Liz herself is downplayed, but hinted to be the worst egotist on the show. She has a view of herself as an intelligent, hardworking, majorly competent, morally just, star writer and feminist icon. She considers her show TGS to be a great, important, and successful show. In reality she's of average intelligence at best, lazy, prone to whining, incompetent and in need of Jack's constant handholding, childish, and a barely known writer who's brief moment in the limelight ended after about a month and who uses feminism as to excuse away her flaws as the work of society's "sexist standards". TGS is actually So Okay, It's Average at best and relies on niche audiences to stave off cancellation.
Just about any contestant on any competitive reality show which requires the contestants to do something, such as The Apprentice, Project Runway, American Idol, etc. American Idol in particular, which has entire episodes full of auditions by bad singers who will not be swayed from their belief that they are the greatest singers in history.
One Villain of the Week of an episode of Being Human was the ghost of a serial killer who called himself "The Toyman" and murdered seven young mothers in the '70s. He sees himself as a Magnificent Bastard and vicious killer. While he is truly evil, he's nowhere near as good as he thinks he is, and his fairly obvious manipulations only worked on the protagonists because of how severely screwed up they all already are. When he introduces himself to Tom and Hal, they clearly have no idea who he is. What makes it particularly funny is he's boasting about a body count of seven to Tom, a lifelong vampire slayer who's staked at least fifteen vampires onscreen, and Hal, a centuries-old former monster whose entire life has been a cycle of bloody rampages interspersed with brief (for vampires) periods of grief.
Sheldon Cooper is a full-blown version of this trope and has traits of Know-Nothing Know-It-All and Insufferable Genius. Sheldon is an extremely smart individual who knows everything there is when it comes to physics, but that's where the positive qualities stop. Sheldon is convinced that he is so much smarter than everyone else that he lets them know it whether they want to listen or not. Sheldon will also go out of his way to correct people who don't have correct knowledge on video games and comic-book superheroes. Outside of Sheldon's comfort zone, he is pathetic and knows nothing about other types of sciences, such as biology. Because Sheldon would rather fight to the bitter end rather than admitting he was wrong, he comes off as completely arrogant and most people can't stand him. Sheldon's apologies are also forced and are mostly not genuine. If Sheldon was in the wrong and he is forced by someone to admit it, then he will make a half-assed attempt to say he is sorry. However, if Sheldon knows what he did was wrong, he will genuinely try to make amends, even if it comes out looking weird. More recent episodes have Sheldon admitting that he has limitations in social situations; that he often has to force himself to be polite or at least tolerate others; and that he is trying to work on the issue.
There are also some hints that he isn't quite as good at physics as he thinks he is, notably when Leslie Winkle fixes an equation he couldn't work out, a Russian physicist/janitor solves a problem he couldn't after just glancing at it, and Stephen Hawking has to point out a math mistake he made.
Howard Wolowitz, or at least the pre-Bernadette Howard, was also pretty much this trope: his turning point seemed to come when Penny lost all patience, gave him the big "The Reason You Suck" Speech, and punctured all his pretentions to the point where he could no longer pretend to be the great ladies' man he imagined himself to be.
Penny displays shades of this in regards to both her social circles and her acting career. She looks down on Sheldon et al for liking science fiction, even outright calling them losers in one episode...even though these "losers" all enjoy successful careers, while Penny is reliant on them to buy her food. She also makes fun of the cast of Star Trek: The Next Generation saying that she knew they were from Star Trek because she's never heard of any of them...this from an actress who's only claim to fame is a crappy BMovie about apes and a commercial for hemorrhoid cream. She's also vocal about how she can do better than Leonard and scoffs at the idea of him doing better than her...even though he previously had done better than her, several times- there was Lesley Winkle, Dr Elizabeth Plimpton, Dr Stephanie Barnett and Priya Koothrappali were all good looking, as well as intelligent and sucessful in their careers. Sheldon's cute assistant Alex also had the hots for Leonard, which made Penny extremely jealous.
Raj has dipped in to this, especially when drunk in the early seasons. Even when sober and in the final season, he once thought he could get in to a Twitter feud with Neil deGrasse Tyson after wasting his time on the news giving potshots at him. The "feud" was predictably one-sided and ended with Tyson personally calling Raj and getting him to back off.
All the title characters in Black Adder, particularly Prince Edmund from the first series. Edmund is cowardly, sniveling, conniving, incompetent and all-around unlikeable. He spends most of his time taking credit for his much more clever squire's ideas, usually only after he's tried his own dunder-headed plan and failed miserably. The other three Blackadders at least weren't idiots, but they spent most of their time insulting everyone around them despite having few, if any, accomplishments to their name.
The Brady Bunch: All six kids have episodes at some point in the show where they deal with swelling egos, only to learn a lesson in the end about humility and keeping things in perspective. In addition, there was at least one episode where a guest character had a huge ego. In the case of "Quarterback Sneak," it is downplayed; Tank Gates, Carol's high school boyfriend, was legitimately talented and had many accomplishments on the gridiron, but he over-inflates his accomplishments.
Brooklyn Nine-Nine: Jack Danger (pronounced "donger") works for...the US Postal Inspection Service that Jake is forced to work with because mailboxes are being used as drug drops. He's an incompetent boob who falls on his when he attempts to chase a suspect, and when Jake tries to give chase, grabs Jake's leg demanding he help him up first. He considers the USPIS superior to the NYPD because it's a federal agency, and dismisses Jake's extensive experience in drug cases to dictate how the investigation will be carried out, i.e. in a stupid way.
Early on Wesley in Buffy the Vampire Slayer insisted he was perfectly capable of field work since he's killed two vampires under controlled conditions. By that point, even the normal characters had slain more than that in actual combat.
Sam Malone, Cheers. He was a former pitcher for the Red Sox who got drummed out due to alcoholism. While he was very charming and quite the Handsome Lech, he still managed to be rather full of himself, dedicating much of the later seasons of the show pursuing Rebecca because she was immune to his charms.
Chang, on the first season, rarely wasted an opportunity to brag he was a tenured professor, which he isn't even close to being.
Britta and Pierce both like to think of themselves as the Only Sane Man of the group, and they're both wrong.
Jeff could be the biggest example on the show. He struts around like the big man on campus looking down his nose at everything and everyone around him, acts like a sex god who is irresistible to women, and clearly believes himself to be the coolest thing ever. In fact, he's a disbarred lawyer who is only at Greendale because he got caught faking his credentials, the one time we see him trying to go into business for himself he completely fails, and if at least one of his former partners (Britta) is to be believed he's apparently not even very good in bed. For all his cooler-than-cool act he's clearly just a big fish in a very small and crummy pond, and it's telling that he gets very uptight and touchy very quickly if anyone dares suggest that he's not the most awesome thing in the universe ever.
Sylvia Noble from Doctor Who is an inversion. She really doesn't seem to have an over-inflated opinion of herself; she just has a really low one of everyone else. Sylvia has no understanding of the concept of tact, often insulting and belittling Donna and Wilf, her own daughter and father, respectively. She dismisses her daughter's disappearance in a flash of light while walking up the wedding aisle as Donna tricking everyone to demand attention. She has absolutely no respect or faith in her daughter, and isn't afraid to tell her so. She refuses to acknowledge her daughter's choices and actions, ignores the Doctor when he tells her there's danger. Fortunately, after Donna's actions in thefinale, she seems to have realized her mistakes, and by End of Time, she's almost pleasant to be around.
More directly applies to spin-off companion Thomas Brewster in the Big Finish audios; Brewster has attempted such scams as stealing the TARDIS and telling former companions that the Doctor gave it to him, or trying to act as a gang boss while posing as the Doctor, but he just doesn't have the skills to pull it off.
Kenny Powers of Eastbound & Down may well be the king of this trope. He's a pitcher who won a single World Series game but whose career took a nose dive due to his insane ego and demands. He still carries himself as if he was the greatest pitcher in history, assumes teams are fighting each other to try and call him back up and he's a beloved icon. He even once faked his death under the belief that "the press will never leave me alone." In reality, most baseball fans (and players) haven't heard of him and those who do consider him a total asshole who threw away his career over his "mega star" delusions. But to him, he's already prepared his Hall of Fame speech in between writing his autobiography.
Batley from Eureeka's Castle. He had such a big ego, one episode saw him singing a heartfelt ballad entitled "I Love Me".
The Fast Show featured the character of Colin Hunt, a loud, obnoxious man who annoys his co-workers with "hilarious" puns, practical jokes and slapstick comedy; and believes that everyone in the office finds this as amusing as he does. When it's pointed out to him that nobody thinks he is funny, he predictably reacts badly.
Fraggle Rock, the Pa Gorg and Ma Gorg claim that they are the King and Queen of the Universe despite the fact they've only had two subjects, specifically their own son and for a very short time Wembley. Everyone else is either unaware of or plainly doesn't care about their claims of royalty.
Theon Greyjoy is a definite example of this, often for comic effect. Theon is an arrogant jerk who likes to boast about his skill as a warrior and being irresistible to women, as well as the greatness of his family (whose rebellion was recently easily crushed, which is why Theon is Eddard Stark's ward/prisoner in a Gilded Cage). The end result is that Theon is often the target of mockery from people of all classes in the feudal system, in the show at least. In the books, Theon is described as a handsome guy that Really Gets Around and doesn't have to pay, he occasionally comes up with clever ideas, is a great archer and fought at the front of Robb's vanguard where the fighting was thickest. Additionally, he's rarely mocked in the actual books, certainly not by prostitutes. In both the book and the series he is then completely and thoroughly broken.
Ramsay parades himself as being the heir to the Bolton line despite his bastard status, Roose is quick to correct him on this.
Ramsay: We've been flaying our enemies for a thousand years, the Flayed Man is on our banners!
Roose:My banners, not yours. You're not a Bolton, you're a Snow.
Joffrey somehow manages to be this despite being King. For all his preening and throwing his weight around, it's immediately obvious to everyone that he's completely inept and out of his depth, and if it wasn't for his grandfather and uncle acting as The Man Behind the Man he'd have been overthrown and impaled on a pike long ago.
As far as Viserys cares, he carries the blood of "the dragon". Nobody else, besides Dany to begin with, gives a hoot.
Daenerys had this problem in Qarth during Season 2. After her name gets a lot bigger in Slaver's Bay, her ego fittingly becomes proportionate to her power.
Balon Greyjoy declared himself the King of the Iron Islands shortly after Robert's Rebellion, but had his own dreams of rebellion quickly crushed under the heel of Robert Baratheon.
Janos Slynt brags almost non-stop about his "powerful friends", not realizing that he's only being used and that nobody likes him, trusts him, or cares about him. He even brags about his "important friends" as he's being led to his execution.
Blanche Devereaux on The Golden Girls. She considers herself devastatingly beautiful and a "mankiller," but the rest of the women dismiss it as a bunch of fluff, rarely taking her stories seriously.
Barry Goldberg - "Big Tasty" considers himself to be a brilliant athlete, a genius at constructing rap lyrics and a crowd-pleaser in every respect. His mother's delusional praise of him doesn't help, neither does his hypercompetitive streak. In reality, Barry Norman Goldberg is perhaps an all-round mediocrity with a big ego.
House: Eric Foreman insists that he's head and shoulders above the rest of House's team, when he's an unexceptional doctor with nothing to set him apart from his co-workers. Chase even calls him out on this in Season 7.
Barney Stinson in How I Met Your Mother thinks his exploits are legen—wait for it—dary! However, this womanizing ladies' man has been repeatedly been shown as lame during several episodes in the series, although sometimes he does live up to his own hype.
Douglas: UNHAND ME, PRIEST! Where is your god? WHERE IS YOUR GOD NOW? FAAAAATHEEEER!!! (sobs melodramatically before seeing Jen) Douglas:Well who's this? Hi, I'm Douglas, what are you doing after the funeral?
Douglas is at least slightly aware of his failures, though. He's just too rich and dumb to stop himself. He is shown to be occasionally successful, which doesn't help, but then stuff like this happens:
Lawyer: Sign here, here, here— Douglas: Look here, I think I know by now where to sign a sexual harassment settlement.
Dennis really stands out. He believes himself to be an immensely charming, likable person who is skilled at everything and liked by everyone. In reality, he is sociopathic, vulgar, rude, idiotic, runs a failing business, and has really only gotten as far as he has due to his family's wealth. Most episodes have him attempt a new venture and becoming completely confused and aggressively annoyed when others don't view him as being talented. Dennis may actually count as "no" name, big ego. It is revealed in "High School Reunion" that he doesn't believe that he has to do anything to earn the respect and admiration of everyone around him and that they should just automatically believe he is a "golden god" simply because he does himself.
In "Who Pooped The Bed?", Dee is shown to think of herself as a graceful Sex and the City-esque starlet, and a compassionate liberal. In actuality, Dee is a crude immoral alcoholic who is willing to scheme her way to the top.
Mac is a Miles Gloriosus who claims to be an expert in karate, but usually gets beat up in fights or runs away. Being The Fundamentalist, he is also a massive hypocrite when it comes to religion.
Frank once claimed he became a millionaire through hard work and earning his money, even though he did it by cheating his business partner out of money.
While Charlie usually averts this, he became one during "Flowers for Charlie" due to being led to think he is smarter than he is.
Perceval and Karadoc, the two most incompetent Knights of the Round Table in Kaamelott. To the point that, on some occasions, they manage to brag about how they epically failed a mission as if it was a victory. Notably, they're convinced that the ridiculous "fighting techniques" they invented make them deadly combattants, while in truth they're utterly inept and usually flee at the first hint of danger. King Arthur beating them both singlehandedly (literally, with a hand behind his back) is insufficient to shatter their delusions. While Perceval sometimes acknowledges his own stupidity and has some heartwarming moments, Karadoc, on the other hand, has absolutely no excuses for bragging the way he does.
It might be easier to count the number of owner/chefs on Kitchen Nightmares who don't show this off. Gordon Ramsay may have won 14 Michelin stars, but to these guys he can't possibly be an actually good chef, he's saying their restaurant sucks!
"Sebastian's" has the title chef/owner a bragging guy with a ludicrously complex menu system and uses mostly frozen foods. He openly talks of his dreams of "franchising" his place, ignoring how the one establishment is a disaster.
Sebastian: One day, my food will be in supermarkets. "Sebastians" all over the world.
Gordon: You haven't got fucking one right yet!
"Pantelone's" has a pizza parlor owner boasting of having "The Best Pizza in Denver." It's from a review...written in 1985. The man insists he's still the best pizza cooker in the city, even after a public taste test has him coming third behind a store-bought version.
Joe of "Mill Street Bristo" openly claims his cooking is the best between New York and Los Angeles. He even plants fake reviews online claiming how great he is. In reality, he's prone to amateurish mistakes with bad food. Gordon soon realizes Joe is under the delusion the reason his place is failing is lack of publicity and Ramsey will boast about his food to others. While Gordon did his best, the place ended up closing down with Joe opening a new diner...which also closed down.
Nothing can top Amy and Samy, the owners of the infamous Amy's Baking Company. Aside from being horribly rude to customers, they blatantly steal tips from their staff and even kick out customers for daring to ask their orders be done in less than an hour. Amy brags out loud about her "genius" as a cook when Gordon finds her one of the worst he's ever tasted. After realizing how delusional these two are, Gordon just gives up and walks out on them.
Hank Kingsley in The Larry Sanders Show. Despite the fact that his sole claim to fame hinges on his status as the sidekick to a much more charismatic and talented entertainer on an average-at-best late night talk show, along with any tawdry commercial spokesman gigs that come his way, he nevertheless throws his weight around despite lacking the respect of almost everyone on the show except his loyal assistant. Played with in that Hank is more than aware of — and deeply resents — his status as the office laughing stock, but is a little too stupid, vain, incompetent, deluded and ultimately pathetic to do anything about it.
Law & Order. John Munchnote When he was a regular on Homicide: Life on the Street got hit with this hard in "Sideshow" (Season 9, Episode 14, original airdate February 17, 1999). He asks to see his FBI file and that he doesn't know if their car will be big enough to hold it. It turns out to be one piece of paper that says he is "considered a dilettante and is not taken seriously amongst the radical community."
Mrs. Oleson from Little House on the Prairie. She thinks her gossip and braggadocio and extravagant gestures make her the true power in the town. In fact, it's probably only affection for her long-suffering husband that keeps the rest of the town from lynching her. Somewhat subverted in that she actually can be quite effective, for a time, but usually in the most vicious situations possible, and after, her stock drops even more.
Married... with Children: Al Bundy was the Big Man on Campus in high school because of his football prowess. He scored four touchdowns in the city championship game in a dramatic come-from-behind win. Fast-forward thirty years, and Al is now a balding, starving Jaded Washout who still clings to the memory of that championship game as the one thing that validates his pathetic existence. He acts as if being a high school football star is actually supposed to mean something, and that people should be impressed when he mentions it. Almost nobody remembers Al's accomplishments, and no one at all cares.
Ted Baxter, the former Trope Namer. Baxter was a newscaster who considered himself incredibly popular, while everyone else in the newsroom thought he was an incredible bore and something of a Ditz to boot, but were (usually) too polite to tell him to his face. Randomly selected from his many blunders: When a broadcast runs short, Ted stands silently in front of the camera until someone hands him a fluff story which he presents as an important news bulletin — and even repeats in the same tone of voice.
Phyllis Lindstrom and Sue Ann Nivens have some of these characteristics, as well.
Major Frank Burns. This is highlighted in "The Novocaine Mutiny," where he recounts for a court-marital hearing the events of a supposed mutiny; he remembers himself as being brave under fire, inexhaustible, selfless, heroic, and of course, a skilled surgeon. The reality is that he behaved just like a sniveling coward, sending patients to the OR without properly prepping them first.
Played with for his replacement, Charles Winchester. The man is indeed a hyper-qualified surgeon (unlike Frank), but his skills were best used in a regular hospital. He finds himself unprepared for the quick-and-dirty "meatball surgery" the camp has to utilize, which gives his ego some much-needed deflating.
Nathan from Misfits is a young offender on community service who remains cheerfully obnoxious and arrogant despite being financially destitute, unemployed, homeless, and loathed by everyone he meets. His friends can't stand him and his parents don't want him around, his sexual conquests almost always end in abject humiliation, and once his power is revealed to be immortality — or rather "resurrection" — he starts dying in increasingly ghastly ways at least once an episode, but always bounces back with a smile on his face. He is utterly convinced that everyone loves and admires him and that women find him irresistible, despite overwhelming evidence to the contrary.
A few of the characters on Modern Family can qualify thanks to the nutty aspects of the family.
Mitchell boasts of being stuck in a well as a kid and no one noticed because it was the same day as Baby Jessica and still acts like she "robbed" him of his fame. He also carries on as if everyone wildly respects his fame from the county fairs of his childhood.
Phil can often think he's somehow a super hot-shot real estate man.
While Jay is highly successful and even rich, he tends to think that owning a major closet/furniture store makes him one of the most prominent and influential men in the city.
Manny is the worst as he's clearly smarter and more mature than the rest of his class and while he sometimes understands his standing, the rest of the time he thinks he's a role model to a class when in reality many kids don't even know him. Best summed up when he stands up at a winter dance to do a big speech:
Manny: I know you all think of me as the golden boy, the wunderkind, the prodigy...
Dan Fielding, Night Court, especially as time went on. A slight divergence in that he actually was generally as successful with women as he expected to be when they were extras. He was also a pretty good attorney, and would generally behave with at least some amount of dignity and aplomb when presenting his side of the case. He was likely relegated to the night court because of his personality, not his skill.
David Brent in the UK version of The Office is absolutely convinced that he's the life of the office and is a world-class musician, philosopher and stand-up comedian. Everyone else he comes into contact with thinks different. He does however seem to be at least partially aware that he isn't as great as he thinks he is, given how he reacts to people pointing it out, or otherwise not treating him as he feels he deserves. For example, when he tried giving Tim career advice which was rejected out of hand, he grew quite agitated, angry and dismissive. Many of David's own illusions about himself are, of course, stripped away by the end of Series Two.
Several characters in the US adaptation of The Office: Michael Scott, Dwight Schrute, and possibly Andy Bernard (though the latter did apparently go to Cornell). Ryan Howard as well, especially after he's promoted to the executive level.
Joan Callamezzo on Parks and Recreation is very egotistical, despite only being the host of a public access talk show. She runs her own book club, à la Oprah Winfrey, and takes glee in humiliating people on her show.
Many customers on Pawn Stars, particularly guys trying to sell cars, often think they did a great job restoring it, but really destroyed the item. One guy removed the air filter so he could fit a larger engine than the car could normally hold. Rick and the Old Man were horrified at the result, and the bozo mechanic claims that they weren't real "car guys" who would applaud the work he'd done.
Jeremy. He thinks he's a talented musician and sponges off his Heterosexual Life-Partner Mark because he won't settle for anything less than a job in the music industry (which no sane person would give him). Despite him being an Unsympathetic Comedy Protagonist, it's easy to see that this actually comes from his insecurity as much as anything else.
Super Hans also counts though he is far more self-confident than Jez. He is equally untalented and pathetic but is often able to get Jeremy to follow Him out of sheer confidence though Jeremy is also able to outthink him quite easily.
While Carlton Lassiter of Psych is a very smart and capable detective, he can occasionally fall into periods where he believes he's a much bigger deal in law enforcement than he actually is and needs an ego check.
The best example is how Lassiter spent years hunting Despereaux, a master thief and boasts of the "epic cat and mouse game" the duo play. When Despereaux is arrested, Lassiter gloats on how he's finally the victor. He's actually jarred when this globally notorious thief wanted by a dozen international agencies flatly states he has no idea who this small-town cop even is.
Marian. She tells Robin that "I do exactly what you do, only with more intelligence." Considering she's saying this while lying wounded after breaking into Guy's house, trying to steal his money, getting stabbed and having to be rescued by Robin, this claim is dubious.
Robin has these moments as well, mostly towards Much, whom he seems to take for granted (technically not his ego so much as the "legend" he's building for himself goes to his head and he ignores good advice).
The sheriff Vaisey also has moments of this, though not to the audience but to other characters. In fact his ridiculous dickery and Jerkass personality was what made him so endearing. But he seems to think he could run the entire kingdom better than the king, even though all he's shown us is he's exceptionally good at backstabbing people and inventing creatively fun tortures. The show's full of them!
In one sketch, Brian Williams played an small-time actor in a high school drama on The CW. While filming the last scene of the finale, he learns that there will be a college spinoff and that he is not appearing on it. He does not take it well, bringing up his brief appearance on Quantum Leap and his "dedication to the show."
Barry: After all I have done for this show. I am on this set every day, whether I have a scene or not. I'm running my lines, I'm running their lines, writing lines-
Director: Yeah, Barry, we specifically asked you not to do any of those things.
Deconstructed in Screenwipe by Charlie Brooker, in which he explores how the "Talent" usually become this in some form. He starts out as an ordinary person who reacts to having someone around to wait on him hand and foot with embarrassment and sheepishness, particularly when his assistant does things he doesn't want or need. Unfortunately, he becomes so used to being treated like this that he takes it too far and ends up becoming an egocentric bully.
The Todd, from Scrubs. He's actually a very competent surgeon, with Turk even jealous when the Todd actually outdoes him. And to his credit, the Todd gave Turk his full support over being Chief Surgeon. His ego instead stems from his sex drive. He thinks he's a sex god, but he's more of an idiot and a pig.
On Silicon Valley Erlich considers himself a cultured genius and top-level programmer who's a major power player in town. In reality, he's an average programmer who lucked out with a single app and sold it for just enough to live on. He's also a constantly stoned egomaniac his own co-workers can't stand. More than once, Erlich has nearly ruined a big deal by throwing his "weight" around, assuming his reputation is intimidating when most in the tech world have no idea who he is.
The much-loathed by fandom Ellis of Smash. He truly believes his offhand comment about Marilyn Monroe is what "created" the musical about her and that everyone owes their jobs to him. He's constantly pushing his ideas and influence as if he's critical to the team, ignoring the fact he has absolutely no experience in theater and that everyone else just ignores him. It reaches his height when he poisons Rebecca to get Ivy the role of Marilyn. He then goes on a massive rant to Eileen on all he's done and demands he be named a producer. Eileen snaps that he's nothing but a glorified gopher and fires him on the spot.
Dr. Rodney McKay from Stargate Atlantis. True, he is brilliant and competent; but NOBODY can be as brilliant and competent as Rodney thinks he is. He mellows out a bit by the first season, but is horribly like this in his first appearance on SG-1. Though his reputation as this trope still hangs over his head back on Earth. In the episode "Brain Storm", Rodney goes to a convention where he meets several Real Life scientists who are well aware of his bloated ego, and they chalk up his warnings about the problem of the week as him trying to act smarter than everyone else as usual.
Comes back to bite him hard in another episode, where his overconfidence that he can fix a power source the Ancients themselves gave up on causes the destruction of a — no, 5/6 of a — solar system. Although, he actually solved an issue the Ancients couldn't figure out, which led to the destruction of the system.
Quark, however, he wasn't an egotist, he was simply an incredibly canny con-artist. Quark is, however, notably successful and an important aspect of the Small Name Big Ego is that they are disliked and don't believe the negative criticism they get. Quark takes being told that he is a conniving backstabber as a compliment, since in Ferengi society, being called a "conniving backstabber" is a compliment. He also developed a good relationship with the Grand Nagus. While he may not be as good as he likes to think he is, he's still pretty good.
Whenever Quark gets his own episode, he routinely pulls off quite impressive cons. These often involved his own acknowledgment that he lacked traditional heroic traits. One of his most memorable was winning a fight by throwing away his weapon. He has even gone into long boasts about his more successful (and generally shady) business negotiations. If the Klingon Chancellor refers to you as "a brave Ferengi," you're doing something right.
This is lampshaded in "Civil Defense". When Quark and Odo (who consider each other Worthy Opponents at the best of times, and nuisances at all times) are trapped in Odo's office while the station is about to self-destruct, Odo (who later says he was just trying to be nice since he thought they were going to die) calls Quark "the most devious Ferengi I've ever met" — a compliment. After the danger has passed, Quark is outraged to find that Odo's real opinion of him is "a self-important con artist who's nowhere near as clever as he thinks he is." Quark's mother has an opinion of her son that mirrors Odo's. It's particularly galling to Quark that she's far smarter and sneakier than he is, which gives favored son Rom great satisfaction.
In another episode, Quark and Odo get shipwrecked while the latter is transporting the former to an important trial involving a criminal organization called The Orion Syndicate. He gets a big laugh when he learns that Quark is not a defendant in the trial, he's an informant. Despite all his boasts about his criminal activities, Quark wasn't considered good enough to join the Syndicate.
Dr. Julian Bashir, who was all of 27 years old and a recent Starfleet Medical graduate at the start of the series, spent much of the first season never shutting up about how brilliant he was and that he could have had any job he wanted, but chose Deep Space Nine because he wanted to get his hands dirty and practice "real frontier medicine". In his first scene, he went so far as to call Bajoran space "the wilderness", right to Major Kira's face!
He also mentioned numerous times that the only reason he was second in his class instead of first was that he mistook a preganglionic fibre for a postganglionic nerve. After Medical experts who watched the show pointed out that the two have nothing to do with each other, and therefore no serious medical professional would ever confuse the two, writers added a reveal that he'd deliberately missed the question the avoid the pressure of being valedictorian. This gets a further Cerebus Retcon after the season 5 reveal that Bashir was illegally genetically enhanced as a child: he really is unnaturally intelligent, and threw his test in order not to draw too much attention to himself and risk exposing his secret. Underneath the apparent arrogance and bragging, he's spent most of his life believing himself to be a fraud, and a monster and freak.
Major Kira is rather irked to find out Cardassian high command considered her little more than a nuisance during the occupation.
Kira: A minor operative whose activities are limited to running errands for the terrorist leaders?!
In later seasons the producers of Survivor have edited Ben "Coach" Wade and "Special Agent?" Philip Sheppard season-long arcs as a Small Name Big Ego. Part of the strategy is a sarcastic edition of the Fake Ultimate Hero, complete with heroic music, but we are ultimately lead to sympathize with the eye-rolling contestants as he goes on more than one Character Filibuster believing himself to be a sage and Warrior Poet, but really proving to be an irritating version of The Philosopher.
Jackie Burkhart on That '70s Show. She thinks she's the prettiest and most popular girl in Point Place and everyone could benefit from her advice. Others beg to differ.
Herb Tarlek, WKRP in Cincinnati. Justified to an extent; as the station's advertising and sales representatitve, a big ego comes with the territory. Herb also seems to know what he's doing as the station sells plenty of advertising slots (very corny local advertising spots are frequent gags on the show) and compared to some of his clients Herb does have some standards.
Xena: Warrior Princess gives us the incredibly annoying Joxer, who frequently sings a sodding song about how great he is. A bad song.
A rare female and Soap Opera example: Patricia Fernandez from Yo soy Betty, la fea. Prides herself of her beauty, her rich family and ex-husband and her "Six semesters on Finances in San Marino U". It's soon pathetically obvious that, if certainly she is pretty, she is also shallow, vain, and a self-absorbed over-spender. Her own family wants nothing with her, and its implied that her ex filed the divorce just to get rid of her leechy self. She soon becomes the Butt-Monkey of the office because of her antics and the official Chew Toy of the Bettyverse.
Rik repeatedly claims to be extremely popular and intelligent, even when people tell him to his face that he isn't. In one episode he actually bets money with the housemates that they like him, because they've just told him that they hate him. Subverted in that Rik seems to know he's an unpopular loser, but buries it under several layers of self-aware denial and bravado. Hell, he cant even say his own name without sounding like a complete idiot due to his Elmuh Fudd Syndwome.
Played straighter with Mike, who repeatedly insists he is a suave and sophisticated ladies man, even though everyone outside of the main cast seem to hate him as much as they hate the others and he is later revealed to be a virgin. The other housemates swing between actually treating him like "the boss" and treating him as if they're just playing along with his delusion.