Prussia, too. Not only is he a Large Ham and Boisterous Bruiser who goes around constantly proclaiming his "awesomeness," but he demands that other characters bow to him and worship him for it. One of his goals, as said by Prussia himself, is to "burn the memory of his existence" into the hearts of others, so that he'll never be forgotten. Which takes on something of a dark tone, as one strip implies that he may be beginning to die or fade away as he's no longer a country.
Unfortunately, one of the characters from Bitter Virgin (Daisuke's self-proclaimed girlfriend, Kazuki) combines this with Yandere and threatens to claim rape if Daisuke doesn't date her. Later on she does try to (falsely) accuse Daisuke of rape, but fortunately no one believes her.
In Brave10, Kamanosuke does not like it when the attention is not on him, and will loudly, violently bring it back if he has to.
The Millennium Earl in D.Gray-Man. In chapter 188, Road and Wisely are seen commenting on the Earl's need to always be the center of attention.
Demegawa from Death Note. It gets so bad that "Kira" Teru Mikami (though Light Yagami approves of his new understudy's taste and timing) winds up killing him. Considering he was The Scrappy who all sides of the Death Note fandom found annoying, his death was a massive relief.
There's also Kiyomi Takada who loves to be the center of attention.
Mr. Satan from Dragonball Z. Note however that this actually works in the protagonists' favor, helping to maintain The Masquerade by claiming responsibility for acts of world-saving or alternately garnering public support for the otherwise unknown heroes. The world has never heard of Goku or Vegeta or even Krillin, but they have heard of Mr. Satan, and will follow his orders without question.
A creepy and very self-destructive version of this trope is Akito Sohma from Fruits Basket. The more traditional version would be Kimi.
A subversion: Haruhi's Attention Whore tendencies are due to to the fact that she doesn't care what anyone thinks of her and her eccentric personality.
Even when she does grab the spotlight, it's a way of getting what she wants, rather than just for the attention. Promoting her club or one of her projects for example.
She doesn't get jealous of attention paid to others for example, although her nature makes it really difficult to upstage her. Nagato manages once or twice, like in Day of Sagittarius
Mayu from Kaguya Hime often pretends to be sick and faints on the spot to get attention.
Kare Kano: Yukino Miyazawa, the main character, puts on the facade of being a perfect honor student because she loves being praised and told she's special. Only her parents and sisters know that at home she's hilariously selfish and vain, while devoting herself so completely toward perfecting herself that she doesn't have a life. She was like that ever since kindergarten, when she discovered that adults would pay attention to her and her peers would look up to her if she excelled in school. Her Love Interest Arima is the first person outside her family who finds out what she's really like and accepts her anyway, causing her to start dropping her act in front of other people as she becomes more comfortable in her own skin.
The Luchadora Castor, a.k.a. Rachel Stanley, in Kenichi: The Mightiest Disciple, absolutely must be the center of attention of all times. If someone is receiving more spotlight than her, no depth is too low to sink to in order to steal it back. She goes as far as to listen to Ma Kensei's advice on what to do.
Sayaka constantly demanded to be the center of attention. Justified because her father was Married to the Job so she tried to show him that she was capable of helping him, and no one valued her unless she proved her worth.
Her younger cousin Yuri was a cranky, loud, attention-seeking brat who wanted everyone to pay attention to her. It's also justified, since her parents were always too busy to look after her.
The titular character of Naruto starts out as one of these as a result of the extreme social isolation he suffered from being the Kyuubi Jinchuuriki. People would actively try to ignore and avoid him, but by acting out and playing pranks he could bring some attention his way, even if it was negative. He mostly gets over this once he makes real friends.
Neon Genesis Evangelion: Asuka Langley Sohryu is desperate for attention due to deeply-ingrained insecurities caused by her mother's psychotic break, subsequent murder-suicide with the doll she called "Asuka", and her father's abandonment. She needs that people acknowledges her existence because otherwise she feels worthless.
Her Rebuild self is notably not this, possibly because its hinted her backstory is signifiantly different. She doesn't really seem to care if anyone pays attention to her at all and her attempts to show off in battle are mostly to prove she doesn't need anyone's help rather than to show off.
Yukari-sensei from Nogizaka Haruka no Himitsu is a big drunken flirt. She'll often make outrageous statements to her class and express disappointment (read: throw a tantrum) if the class doesn't react as she likes or ignores her.
One Piece gives us "White Horse" Cavendish, a Bishounen pirate who was all the rage and loved every minute of it. That is, until the antics of Luffy and the rest of the Eleven Supernovas at Sabaody and Marineford overshadow him. Now he wants to kill them for making him old news. Luffy himself points out how stupid this grudge is. Even possessing a Superpowered Evil Side, normally considered a bad thing, doesn't bother Cavendish because it results in even more attention coming to him. In spite of all of that, however, he's an overall good guy, especially after Usopp saves his life, resulting in him giving up his grudge and becoming Luffy's ally.
The Ax-Crazy Intention of the Abyss from Pandora Hearts certainly qualifies. She gets angry when no one listens to her, and even kills a chain because it INTERRUPTS her while she's talking. At which point, she goes psycho and starts laughing and dancing in the blood. She is conceited and vain to the point where she even tries to lure away the main character from his chain, Alice the B-rabbit, simply out of jealousy.
Sae from Peach Girl. This is pretty much what drives her to do everything in her power to undermine Momo because she's jealous of Momo for gaining the attention of their sought after Bishōnen classmates Kairi and Toji, and she wants to remain the most popular girl in school. In fact, she gets extremely nervous whenever it appears Momo is the focus of their classmates attention.
In Pokémon, Team Rocket's very own Jessie LOVES being the center of attention, which is why she decides to compete in Pokémon Contests and Showcases, and gets really angry when the reflectors aren't on her.
One of the possible interpretations of Autor in Princess Tutu. Although he comes across as a loner, he sets up a dramatic meeting with Fakir and quickly offers him his knowledge of Drosselmeyer, seeming rather giddy about the chance to get to show off. On top of that, when he runs into Rue and is instantly attracted to her, he flirts with her by... talking about himself and how great he is. He even has several cameos showing him yelling at people in the library to be quiet, and quite possibly making even more noise than the offenders were. He seems to have an inferiority complex, which doesn't help.
Sayonara, Zetsubou-Sensei: Probably the motivation behind Nozomu's attempts at suicide every action. There's also Nami Hito, but her Attention Whore tendencies only really show in her first appearance, in which she tries all kinds of gimmicks to gain pity and attention from her classmates (culminating with a threat of suicide). They all fail, of course.
This is pretty much proven when it's revealed that everything in Nozomu's suicide kit is designed to not kill him, and that he regularly goes to the gym to strengthen his neck to survive his frequent hanging attempts.
Nozomu: *after an attempt to save him from hanging himself nearly kills him anyway* What if I had died!?
Panda from Shirokuma Cafe. Once he heard a magazine was coming to check out the cafe, he starts preening in hopes of getting interviewed and his picture taken. He also tries out different jobs at the zoo and returns to his original job after seeing how many compliments Llama received for portraying Panda, and has gotten angry at how much attention Shirokuma received compared to him when the gang go to the beach.
Slam Dunk: Hanamichi Sakuragi's biggest flaw is this.
Tantei Team KZ Jiken Note: Wakatake is noted to "like to stand out" in the official character bios. A more specific example would be at the end The Egg Hamburg Steak Knows arc, when he lost the chance to make a press conference over the pork contamination of burger patties (owing to the company in question declared a recall themselves), he ends up in a Corner of Woe...
Uesugi: In other words, the problem is with Wakatake's character.
Origami Cyclone in Tiger & Bunny (at least, the superhero persona; Ivan himself is more of the shy type.) Because his powers, while useful for more stealth and espionage-related activities, are useless in the world of theatrical heroics, he's unable to do much crimefighting on Hero TV. Fortunately, since Hero TV is as much about corporate sponsorship and Product Placement as it is fighting crime, his sponsors find a different use for him: constant photo-bombing.
Saki from To Love-Ru. It never works, as Lala keeps inadvertently upstaging her.
Ami from Toradora! is behaving like this for Ryuuji, at the beginning.
Misaki from Welcome to the N.H.K.. In the manga, when the self-inflicted cigarette burns on her arm don't impress her schoolmates, Misaki cuts her wrist to get attention.
Real Account's Ayame Kamijou reveals she is this when her team has to pacify the giant "Attention-Chan" robot before it explodes. In Ayame's case, she came to rely on her brother's attention excessively when her classmates started ignoring her, even to the point of obsessing about him texting her and constantly clinging on him. She even continues seeking his attention after he essentially leaves her for dead to save himself. Attention-Chan is actually also an attention seeking middle aged man, who started pretending to be a girl online after his wife left him so he felt supported and doted on. Ayame's own 'expertise' proves to be a method of victory, and she admits it is something she needs to work on.