Most overpowered characters in gaming...

[Rase]

[Hollycat]

combo

[*Laurelindo*]

Dias in Star Ocean: The Second Story is quite overpowered when you first get him.

Otherwise I'll have to say Hero from Dragon Warrior 4, that guy is an ace at everything (best equipment, Healusall, Lightning and Thordain).

[Skyblade]

Nephenee, from Fire Emblem: Path of Radiance.

The series' first playable member of the Soldier class (since the games came to America), and easily the second best character in the game (second only to Ike, who is probably the single most overpowered character a Fire Emblem game has ever had). She has excellent max stats once she is promoted to Halberdier, and a really sweet stat growth that has a tendency to give her boosts to pretty much everything most level ups. She also has access to the Flame Lance (and better Magic growth than most lance-users), making her one of the few characters who can reliably deal both physical and magical damage. And she looks awesome.

[Raistlin]

Suikoden V: Richard, Georg', Zerase, Belcoot, Killey, Mathias, and Roy.

I think Richard blows the rest of them out of the water. When you had to split into three parties for the final dungeon, I had a lot more difficulty with the other parties because I actually took damage, which is almost an alien concept for a party with a fully-utilized Richard.

For Lunar SSSC, both Laike and Ghaleon are very overpowered when they are in your party. Laike especially, with his four or five super strong hits per round (Alex and Kyle become pretty damn overpowered when they get more hits too).

[Shattered Dreamer]

Shadow in FFVI before he joins you permanently is overpowered compared to the characters already in your party. He's the only non main protagonist who's overpowered I can think of right now.

[Polnareff]

Magoichi Saika in Sengoku Basara 3 has it all: good speed, really good attack, great range, and she only gets better when you equip her with certain items. She's so good that my friend, who never plays crowd-control games, was able to get through the whole thing with a barely powered-up Saika on the hardest difficulty with no trouble.

I'd throw Kanbei Kuroda in there too (from the same game as Saika), but only if you can master his roll cancel. You master that and learn the timing of his Final Atomic Buster-like super art to get all the throws out of it, there's no way you'll have any trouble beating his story mode. Do his regular combo, then the wrecking ball swing move, cancel into the shockwave, roll as the shockwave finishes animation, and do it all over again and you'll pretty much steamroll over everything. The bosses die quickly to the Final Atomic Buster, usually within only two uses of it.

Nicole from Guardian Heroes was a healer, but a really kick-ass one. Not only did she have awesome healing spells, she had some really fast attacks and the barrier of doom. With the barrier you could trap bosses in the corner of the stage and make them bounce off the barrier until they died and protect yourself from attacks too. The only bad thing about it was that you didn't gain experience for hitting them with the barrier or even killing them with it.

Even though Blue Dragon is quite easy, I seem to remember having Marumaro as a Monk and decimating a lot of monsters by himself (he had the Chakra ability, he had a move which hit every monster in the other party, and some other really crazy things). Just scary. Having Jiro with healing spells and Shu and Kluke whacking away made the game probably the easiest RPG I've ever played.

[Vermachtnis]

Pamela from Mana Khemia.

She's a ghost so, she get's Null-Physical. Also she has an auto Auto-life skill, it's not automatic, but it's not a long wait time either, so if you just hold out for awhile, she'll come back. Not to mention, she has an attack that get's stronger the less health she has and another attack that's cast from health.

[Hollycat]

Having Jiro with healing spells and Shu and Kluke whacking away made the game probably the easiest RPG I've ever played.

Dak is in blue dragon!??!?!

[NorthernChaosGod]

Meta Knight is ridiculous in Super Smash Bros. Brawl. He has awesome recovery, crazy speed and priority.

[Polnareff]

I was able to find a video of Nicole.

YouTube - ‪Guardian Heroes speed run 26:16 Nicole pt1‬‏

Forgot to mention she has a move that's B+C I believe, and knocks the enemies away and is almost totally invincible (it's that one she does where a blue beam rises vertically around her). Only downside is it takes a little life away from her, but remember the healing spells? Ah.......

[Laddy]

Pamela from Mana Khemia.

She's a ghost so, she get's Null-Physical. Also she has an auto Auto-life skill, it's not automatic, but it's not a long wait time either, so if you just hold out for awhile, she'll come back. Not to mention, she has an attack that get's stronger the less health she has and another attack that's cast from health.

Agreed 100%!

I'd have to say Aigis of P3, imo. She was pretty much unstoppable.

[Shattered Dreamer]

I thought of another one:

Brock Lesnar in WWE Smackdown Here Comes The Pain on PS2

That ahole was next to unstoppable! I play those games on their hardest difficulty (I find them quiet easy) but even on normal this guy was a bastard. I remember he used to be able to kick out of your finisher even when his body damage was in the red. I really really hated ever playing against him the dirty smurfer!

[Hollycat]

anyone with the satellite laser in 3rd birthday.
The only thing those guys cant take down is the reaper

[Giga Guess]

I'm hard pressed to think of anyone more blatantly overpowered than Orlandu from FF Tactics. Let's look at the facts:
1.) He's a storyline character. No additional effort must be made to find him AT ALL.
2.) He comes equipped with one of the most powerful swords in the game.
3.) He renders three whole characters almost completely redundant (Granted, one only is in your party temporarily) and stops shy of completely eclipsing the other two purely because they are female, and can equip Chantage, and he cannot. Hell, you even get one AFTER him.
4.) Most importantly, he enters your party, and pretty much every subsequent battle becomes all but completely trivial. His stats, the effect, and power level of his attacks...granted, one should expect it when one earns the moniker of "Thundergod Cid" but yeesh!