Tsundere/Web Original

Usually tsuntsun ("Type A")

Web author Twisted Hilarity's popular story The Last Pure Human features Max, who finds himself centuries in the future on an alien planet after being cryogenically frozen on his way to a colony, Exty Years From Now. To summarise, he finds himself unwillingly 'married' to giant alien Cat-Man Kasan: cue a long, long series of "I hate him. I'm not even gay. I am totally not into his huge hot body. I am not going to lead him on, especially not when he does that sexy smile of his. Nope. Not one bit." Thankfully this grows less prominent as the story goes on.
Both Sasha and Daichi from Greek Ninja are this.
This girl from Not Always Romantic.

Its Just Some Random Guy: Random Gal... And HOW!!
Yahtzee comes across as a Tsundere whenever he has to grudgingly admit that he actually likes something. The fanbase has picked up on this, too.
Neil Gaiman apparently thought of George W. Bush as being Tsundere towards Saddam Hussein.
Princess Peach in this video. Mario and Bowser actually gush over how Tsundere she is!
- Although that may actually be a subversion; she's not being "tsundere", she's just sick of them both and their ugly faces, not to mention this whole fruitless kidnapping/rescue thing.
Church from Red vs. Blue probably fits in here somewhere. He's a jerk most of the time, but on occasion shows that he really does care about the rest of his team (and about Tex). The instant he realizes that he's done so, however, back comes the tsuntsun side. Tex is just plain tsuntsun, though. It particularly shows up in this episode when Tex and Church confront O'Malley.
- In season 8 his deredere side comes out a bit more. Then again, it's kind of maybe not quite the original Church.
Jon from The Runaway Guys.
"Tsundere shark" meme - start with a shark photo, add Luminescent Blush, "relevant" Stock Phrases and perhaps big eyes.