9. Arcade - Avengers Arena
For years, Arcade seemed like the punchline to a bad joke. This Marvel villain was a professional hitman who tried to assassinate heroes by building amusement-park themed deathtraps, specifically tailored to each target. These “Murderworlds” were a wildly impractical (and no-doubt expensive) method which killed less people than most actual theme parks.
That, combined with the questionable fashion sense of a white suit and polka dot bowtie, makes you wonder why anyone would ever hire this guy.
However, Arcade would become much deadlier in Avengers Arena by Dennis Hopeless. Inspired by a certain series of young adult novels, he kidnapped a group of teen heroes and forced them to fight to the death on his own private island.
Murderworld finally lived up to its name as numerous characters were killed off and even Arcade became a threat, using a mixture of technology and magic to give himself full control of the island and disintegrating Avengers Academy student Mettle.
Even though the surviving heroes managed to escape, Arcade managed to evade justice at the end of the series. However, he would get his comeuppance in the sequel Avengers Undercover, ending up strapped to the front of a stolen SHIELD Helicarrier.