I actually had to think about this one, because the villains in Reboot are all pretty awesome, even Megabyte, whose schemes are always foiled by Bob, and yes, even Daemon, who was kind of a lackluster baddie, considering how powerful she was. One-shot villains, like the infected Guardians from Season Three, were also pretty badass, as shown by the yellow-skinned woman who fought AndrAIa, High Noon style, and most were really well-developed, with a clear arc for their journeys. Pretty impressive for a thirty-minute, computer-animated TV show from the early to mid-90s, if you ask me.