4. Sub Zero I
This Sub-Zero is notable, as he only appeared in a single Mortal Kombat game - the original. Storywise, he was killed by Scorpion, became a ghost, and changed his name to "Noob" (after playing way too much Call of Duty). But for that one game, he was a beast of a player - his set of freezing-oriented moves could be devastating, and was easily one of the best characters in the game. Granted, there were only 7 characters to choose from, but...at least he was still better than Kano?
Editor's Note: Classic Sub-Zero was also in Ultimate Mortal Kombat 3, even though he was dead? I'm beginning to think these developers were less concerned with following a logical story and more concerned with making a fun goofy fighting game.
Here he is - the God of Thunder, the eternal being and former Protector of the Earthrealm (and guy who fought in a tournament with a Hollywood actor and a dude with one eye). Raiden's big things are (obviously) electricity and wearing a hat (the non-blade variety). And while one of his signature moves is babbling incoherently while torpedoing himself into people, electrical attacks make up the majority of his moves, making him sorta like the Emperor in Star Wars (except not an evil California Raisin).
2. Sub Zero II
This is the 2nd (and the one you're actually probably familiar with) version of Sub-Zero - Sub-Zero II, the younger brother of Sub-Zero I, whose mom told him he HAD to let his little brother play in the fate-of-the-world murder-tournament. Sub-Zero II is, essentially, the exact same character as the original Sub-Zero, with the same powers and appearance (although in MK3, he dropped the mask, got a scar over his eye, and had less ninja-clothes). Not to diminish Lil' Sub-Zero though - his abilities are some of the best in the series and he's obviously an insanely popular character. But there's one character more beloved than the blue ice ninja. It's...
The undead hell spectre, Scorpion - who has perhaps the most iconic quote/ability in the entire series: his shout "GET OVER HERE" followed by a spear-rope shot out of his hand that would drag his opponent to his feet. Then again, I don't really need to explain that to you. That's the beauty of Scorpion - everyone knows Scorpion and what he's about. He's the face of Mortal Kombat, even if he doesn't actually have a face himself.
(BTW - just in case you were confused which ninja this is, he's the yellow one)