Well, if we're firing away at the 0% margin:
Zergling Duo
Seriously, imagine it. A pair of Zerglings, in a dark parody of the Ice Climbers, ready to kill and eat... well, anything.

Now imagine a pair of these little bleeders running amok.
Odds: 6% (there was StarCraft 64... and StarCraft is pretty popular)
Big Daddy
Ah, yes. The Big Daddy from Bioshock. I don't think an image is necessary; if you've been following gaming, you've seen this brutes. Heavier then Bowser? Check. Suprisingly fast? Check. Sound absolutely terrifying? Check.
Odds: 1% (if they were to announce Bioshock for the Wii, it'd be one hell of a way to announce it.)
The Prince (A.K.A. the Arrogant Man)
I doubt anyone can come up with something more unlikely then this.

See the gentleman in the portrait? Not the guy with the hat. The faceless thing with blood dripping down its mouth. (Well, it doesn't have a mouth, but you know what I mean...)
That's the Prince from Ben "Yahtzee" Croshaw's freeware old-school adventure game, "Trilby's Notes." (The same Yahtzee who does "Zero Punctuation"; you may have heard of him.) (Oh, and Trilby's Notes is 3rd in a 4 part series, if you're curious.)
Some explanation is needed here, as I doubt I am surrounded by old-school adventure game enthusiasts. The Prince is about seven feet tall and carries a long metal pole. He teleports in behind his victim, raises the bottom of his pole above his victim's head, and plunges straight down, impaling them. Nasty. He continues impaling them until he gets tired. For a quicker execution, the Prince teleports in (sensing a pattern?), snaps his victim's neck, and then teleports away. He's got a taste for blood and cruelty, serves Chzo, the God of Pain (no relation to the Chozo of Metroid), and is generally not a person you want to bump into in a demon-infested hotel. I could count the pixels used for the Prince (it's Old School), but he's still genuinely scary once you get to know him.
Odds: <0.01% (
Never say 0%. Trust me): He's from an ultra-obscure PC-only freeware adventure game, and he leaves a trail of blood everywhere he goes. (Notice the hotel bar's decor? It gets worse, trust me.) I politely challenge this forum to top that.