The DVD release of Dr. Horrible's Sing-Along Blog contains a commentary track entitled "Commentary: The Musical". One of the songs in the musical is actually titled "It's All About Me", and consists of small sections sung by each of the extras in the production, explaining how it really is all about them...
There is a song from The Batterys Down in which a Jewish 13-year-old sings about how her bat mitzvah is all about her, so everybody better practically worship her.
Homestar Runner gives us the now legendary Strong Bad, whose self centered-ness is rivaled only by his self-perceived awesomeness.
The Nostalgia Chick pays little attention to any feelings or problems that aren't her own. It's not clear whether she even notices them or just doesn't give a crap.
A number of reviewers on That Guy with the Glasses fit that description as well. The cast commentary for Suburban Knights has them lampshade how selfish and hate-filled their characters all are to each other, although Doug's own commentary calls attention to how they're more like a fucked up but caring family and how Joe still sat down after his Big "NO!".
Gaea thinks of her guildmates as human shields, gets away with not contributing to the guild's common fund under the pretense of (not really) low finances while the very same guildmates are probably worse off than she is. She actually says the following line while explaining what scouting consists of to The Watson in the webseries : "Your'e supposed to make sure there is no danger for me... I mean us.".
Omega Zell, usually the Butt Monkey, tends to try diverting any kind of positive attention the guild gets to him. He also keeps claiming that he will be soon in the game's best guild despite the fact that he got on its recruitor's bad side, somehow convinced she will forget that he's a JerkassStraw Misogynist once she gets to see his talent.
A great amount of the customers featured on Not Always Right fall into this, as they believe "the customer is always right" means "you must serve me and me alone perfectly".
The Twilight Sparkle in the universe of Friendship is Witchcraft is a totally self-absorbed geek who can't comprehend the fact that the world doesn't revolve around her. While the series starts off treating this for (comparatively) lighthearted laughs, Twilight's character descends further and further into Black Comedy as it becomes clear just what a morally-bankrupt monster she really is.