Being a trolling-based site, Encyclopedia Dramatica is all about this. From showing all the spoilers at the top of the Harry Potter page to redirecting you to shock images when you search for "kittens", the wiki is the very embodiment of this trope.
A more serious example would be the Director, who has a serious lack of empathy for almost anything.
Gordon Freeman is depicted having this kind of personality in Freeman's Mind. He hides it well by being a Heroic Mime, but his inner monologue holds nothing but contempt for almost everyone that crosses his sight.
James Potter in the fanfic series "Adventures with the Potterz." 
Global Guardians PBEM Universe: The Aryan is a Flying Brickcrimefighter who also happens to be a white supremacist. He absolutely repudiates violence against non-whites (except, you know, when they are non-white criminals), and saves the lives of non-whites as often as he does whites (he believes that by doing this, he is showing himself and his race to be "good examples), but is nonetheless a racist asshair and is quite vocal about his views on race relations.
Almost all of the good guys in A Very Potter Musical qualify, but Harry takes the cake. He's got an ego the size of the sun, constantly rubs it in the faces of all the other characters, and thinks the fact that he's Harry Potter makes him entitled to everything. By contrast, Voldemort's actually a pretty nice guy. Ron, too, especially since he explicitly says "I know I've been a Jerkass lately" when apologizing to Hermione.
Every character in the web series Sanity Not Included is a jerkass, but extra points go to Lyle for having the last name McDouchebag to emphasize this.
Jonas from The Platoon Of Power Squadron has quite the mean streak. There was even a comment on one of the earlier episodes when the team's powers weren't yet clearly defined asking if his power is “being a dick”.
Sonic from Sonic For Hire is an extreme jerkass. 85% of the other characters in the show have their jerkass moments too.
The Meme character Scumbag Steve, obviously. He is especially amoral at the matters of girls, drugs and parties. His iconic hat has achieved even more meme status than himself, though, to the point that if you crop the hat into a picture of any human/animal/inanimate thing, that human/animal/inanimate thing will automatically become a jerkass. The real guy behind the picture is actually a lot less scummy, though he's since embraced the meme in a self-deprecating way.
An example is "Scumbag Alkohol" which describes all the stupid things you may do when drunk (for example texting to your ex that you love her and stripping naked in front of the whole party) and features a picture of a vodka bottle wearing the hat. The vodka bottle is treated as if it's a sentient being who talks to you and suggests you to do all these things, convincing you that they are good ideas.
Other examples are alarm clocks and even your stomach which are treated like people from foreign countries who want to teach you about their culture even if you are not at all interested, thus playing you "the song of their people" at very inappropriate times (that is, beeping in case of the alarm clock, growling/farting in case of your stomach).
Steely Dan in Vaguely Recalling JoJo. Dio and J. Geil cannot forgive him for hurting and lying to Enya Geil. He also treats his part-time worker abbd Jotaro like crap.
In the YouTube Poop "Link is on Strike", Link plays this straight, if not taking it to an extreme. Sure, Link has dealt with a lot of garbage before, but that doesn't justify Link's behavior in this poop. He insults everyone, and even when King Harkinian tries to make peace offerings, Link still refuses. Even after...well, you might know if you watched the video...he still refuses. To put it simply, Link is a manipulative bastard.
A jerkass has a brief appearance in 20 Reasons Why NOT to Be "In Da Club" by Matt Santoro. A man named John is chatting it up with a girl at a club, and an unnamed man suddenly comes in and mentions that John has herpes. John is not happy.