Amy Farrah Fowler of The Big Bang Theory tends to fall into this, like when she became Bernadette's Maid of Honor.
"Today is not about you! Today is about Howard and Bernadette and me!"
Bernadette: Were just trying on dresses, do we really need to record this?
Amy: Iím sorry, are you the maid of honor?
Bernadette: I am the bride.
Amy: So no.
The main character of Selfie, Eliza Dooley, is a little like this. In her every day life, she doesn't need to be at the center of attention, and often ignores her co-workers, who don't really like her. She is however, all over social media, constantly tweeting, taking instagram pics, and so on. It seems to be due to being ugly and alone when she was young, and know she craves affirmation from others, based on shallow things like her looks.
Liz: You're so insecure you get jealous of babies for their soft skin! Jenna: And how much attention they get.
Jenna's response to finding a positive pregnancy test in the trash?
Jenna: Oh, no. Someone's going to get more attention than me.
Jenna: Oh, don't be so dramatic. That's my thing and if you take it away from me, I will kill myself and then you.
While out shopping with Liz:
Jenna: We need to get out of here BEFORE SOMEONE RECOGNIZES ME!
Jenna: Last night was a disaster, and not the good kind where I get to sing at a benefit.
Jane on Coupling. When viewed through "subtext vision", all her speech registers as "Let's all talk about me!" Oliver even reasons that Jane says weird things just to seem provocative, and probably isn't even really bisexual, if she were to be completely honest with herself.
Both Nathan and Alisha from Misfits pretty much fit the bill, which is probably why they don't like each other much. Although Alisha at least seems to prefer positive attention, and she shamelessly flaunts her body, flirts and simulates sex on inanimate objectsnote the "bottle scene", anyone? to get men to notice her and do what she wants (it usually works like a charm... but whenever it doesn't she assumes the man in question is "gay"). Nathan, on the other hand, seems unable to discriminate between positive and negative attention and just desperately needs everyone to be noticing him all the time regardless of the circumstances. He occasionally goes to jaw-dropping lengths to make himself impossible to ignore. And usually ends up getting hit by someone.
Alisha grows up a lot in season 2, and probably doesn't qualify as an Attention Whore any more (although she definitely did in the beginning). Nathan, on the other hand, is shameless as ever - he thinks nothing of taking a dump on someone's bed just to prove a point.
Trina from Victorious. This actually goes to the point where she sells the song that Tori wrote for her "birthweek" and passes it off as her singing, despite not being a good singer at all.
Ricky of Noah's Arc, whose promiscuity is at least in part due to this. In fact when his employee doesn't actively pursue him he relentlessly tries to understand why, actually confronting the employee about it.
Pretty much the prime motivation of most people on Reality TV shows.
Rachel from Glee. She sent a prospective club member with a really good voice to a crack house so that she wouldn't upstage her, then tried to pass it off as protecting the roles of the others. Finn calls her out on this, but it's too late by the time he does because the prospective member's already been taken up by Vocal Adrenaline thanks to Sue.
Series/NCIS features this in shades. One notable instance is in the episode "Murder 2.0", where a serial killer broadcasts his murders on a YouTube expy, all for becoming famous.
Jen from The IT Crowd doesn't always act like this, but her behavior includes singing loudly (and badly) to announce her newest relationship, complaining constantly about problems to her (usually uncaring) co-workers, and pretending to speak Italian when she can't because no one was paying attention to her and because another woman's performance at work was outshining her own.
Michael Scott has a veritable laundry list of attention whore moments.
At Christmas, he insists on being Santa, even though there's already a Santa. He even goes as far as to dress as Jesus Christ at one point, insult everyone via karaoke machine, and complain about it to David Wallace.
Another Christmas party has him buy Ryan an iPod for a gift exchange with a twenty dollar limit.
At Phyllis and Bob's wedding, he tries to get into all the pictures and feels he needs to keep talking, even though he only has a minor role in the wedding.
At the Dunder Mifflin shareholders' conference, he was only supposed to wave when he was introduced, but he insisted on giving his own version of a pep rally.
When Dwight goes to the hospital for a possible concussion, Michael insists on talking about the burn on his foot and even goes so far as to try to stick his foot into the MRI machine when they're scanning Dwight's head.
In every meeting he attends, he tries to be the center of attention.
He comes up with "Scott's Tots" as a way to get attention by claiming he will pay for college for a bunch of kids, but then doesn't follow through. He did it all for the attention he got.
He creates his own presentation to compete with the sensitivity training.
When he is on board ship and no one is paying attention to him, he goes so far as to claim the ship is sinking!
Kelly constantly lies to her boyfriends that she's pregnant to get them to pay more attention to her, one of her New Years Resolutions was to focus more on being the center of attention, and at one point mentioned that she's taken it so far that she can't get people to do anything for her unless she threatens to kill herself, which she evidently has no trouble doing.
This type of character makes up the vast, vast majority of Rik Mayall's body of work. This live appearance at Comic Relief in the mid-'80s says it all.
The Doctor of Doctor Who can drift into this at times. He rather likes to be admired and adored, and that's part of both his hero complex and the reason he has companions (besides the many, many other things they do for him.) On the other hand, he does always leave before he can get credit for all the life and universe saving he does.
Doctor: I'm being extremely clever up here, and if there's no one to stand around and look impressed, what's the point of having you all?!
The First Doctor is naturally reclusive and secretive out of concern for his own safety, but has his moments of attention-seeking. In the first part of "The Time Meddler", he very blatantly fishes for attention from Vicki in order to make himself feel less lonely after Ian and Barbara's departures, monopolising her time and Compliment Fishing. In "The Savages", which is the first time the First Doctor lands on a planet which not only knows about his travels but considers him a great hero, he smarms and mugs his way around the planet, ordering his fans about, letting them dress him up in fine clothes, and mentioning to his companions that it's about time someone gave him this sort of treatment.
The Fourth Doctor was by far the most unsubtle one about it. This is noticeable especially when entering rooms, which he would accompany with striking a pose, or a huge amount of googly-eyed flailing, or usually some mixture of both. If he didn't get a good enough reaction he would sometimes leave the room and do it again. Sometimes, if another character was talking and everyone else was paying attention to them, he'd fidget about and gurn in the background until everyone got distracted, or just blatantly interrupt the other person just so that people would look at him. Like many performers who come out of repertory theater, Tom "I Don't Need a Companion" Baker was drilled to shamelessly steal scenes and stand front center at every opportunity.
In one episode, he has a Funny Background Event where two characters are having a conversation between themselves which happens not to involve him. He stands between and behind them, looking between them with his mouth open ready to interrupt, slowly becoming increasingly distraught that neither of them are paying attention to him, and then shoots them a look of contempt and wanders off.
Notably averted by the Ninth Doctor, so far the only Doctor to actively eschew attention - unlike his predecessors he tends not to charge in headfirst and start demanding everyone listen to him, instead preferring to hang around in the background using a combination of Obfuscating Stupidity and general invisibility to blend in, observe what problems everyone else is dealing with, and then sneakily sort them out while no-one is looking. Of course, the least attention-seeking Doctor is the one who ends up forced to appear on a sadistic reality television show, which would have caused much egotistical mugging from any of his other incarnations (especially the Third, Fourth, Sixth and Tenth) but is an excruciatingly embarrassing experience for him.
Sherlock also likes lots of attention, and in the first episode he clearly enjoys it when Watson tells him how fantastic his deduction are. Later he says of Moriarty that 'genius needs an audience', to which Watson gives a non-committal answer, because Sherlock likes an audience too.
Tim becomes one in one episode of Home Improvement when Al temporarily takes over for a cooking show with Tim as his assistant. Despite the role reversal, Tim continues to try to be the center of attention like he does on Tool Time, and eventually has to learn to back off and let Al have the spotlight (at which point they suddenly switch roles again, with Al becoming the clumsy lead and Tim being the Straight Man sidekick.)
Tjolk Hekking, the deputy of major Hans Van der Vaart, who always tries to get attention by placing himself in front of the major and Spiking The Camera.
Arie Temmes, who brags about his act of resistance during World War Two, while he actually did nothing else besides telling a German officer the wrong direction to the station. Despite this, Arie still fantasizes how this deed might have changed the outcome of the war.
Prof. dr. ir. Akkermans, who invites the press to his home because he claims his "name was mentioned" for about every important business position.