5. Hammer (Super Smash Bros)
Smash Bros. is a chaotic enough game as it is, without giant, Thor-like hammers raining down on the tiny platform that is the only thing standing between you and certain death. The Hammer turned you from an average plumber/humanoid fox/F-Zero driver into an unstoppable god of destruction, while everyone else helplessly grabbed for Mr. Saturns and those stupid bumper things.
Thank god there were options to specify exactly which items you wanted to appear in multiplayer Hammers are the first thing gone in most peoples lists. Although, if you really want to experience Smash Bros. at its finest: Final Destination, only Hammers. Welcome to Hell.
4. AWP Sniper Rifle (CounterStrike)
Maybe the most infamous overpowered weapon of all-time, the AWP was the source of constant frustration, swearing, and inappropriate slurs during many a Counter-Strike match. It was a long-range, one-hit kill weapon that even mediocre players could use to dominate a map. It's really amazing how insightful people can get about your sexuality simply from your weapon choice in a videogame.
3. Thunderbolt (Mario Kart series)
When talking Mario Kart, most people instantly go to the dreaded Blue Shell as the most overpowered weapon in the game. And they have a point: it targets the first place racer, it's (nearly) unstoppable, and it's incredibly quick. But Thunderbolt is one better it affects every single other racer (unless they're protected by a Star, Bullet Bill, or have fallen off the track) and shrinks them, making them vulnerable to pretty much anything and slowing them down so significantly that they won't be able to make normal jumps, which could set them back halfway through a track.
One of the more devastating reasons that Thunderbolt is a better deal than the Blue Shell is that the Blue Shell is useless to you if you're able to get in 1st place with the item in tow. If you fire that off, it will actually still hit you. But saving the Thunderbolt for 1st place puts you at a crazy advantage, slowing down everyone even though they're already behind you. Even a well-timed Blue Shell usually isn't enough to stop you when you've got the power of lightning. God bless Ben Franklin for inventing it.
2. BFG9000 (Doom)
The original overpowered gun is also one of the greatest. The BFG (or "Big Freakin' Gun" according to my mom, who took the manual away from me before I got to that section) did crazy damage to anything that got in its path, and was an insta-kill to anything that got hit head-on. The green orbs reduced everything around you to a pile of goo, and the rest of your weapons were instantly pointless. Even the big bad of the game, the Spiderdemon, can be taken down by just two shots from the BFG. It's sorta a cheat, but it's nice when tearing through Hell is easy as a hot knife through butter.
1. Knife (Like, a Whole Bunch of Games)
The knife is the most unholy, powerful weapon in the FPS genre. It is almost universally a one-hit kill, silent, and undetectable. It has unlimited ammo. Sometimes it can even be thrown. And it's just a fucking knife.
The intent of the All-Powerful Knife is to reward stealth and sneakiness over the typical run-'n-gun strategy most employ in multiplayer matches. The problem is that a lot of the time a player could be running directly towards you while you fire bullet after bullet into their body, and with a single stab, you're dead and they're off ordering airstrikes. Somehow your bullets to their chest did little-to-no damage, but their puny knife swing cut you in half. That's not stealth. That's not strategy. That's not reasonable.
That's Friday the 13th.