Mad Hatter Mind Control

This one is iffy enough that I almost don't want to include it, but I will.

The Mad Hatter was a very minor Batman villain for a long time. His first appearance, all the way back in 1948, was pretty much just as a generic thief with a gas gun. He appeared two more times - once in the 50s, once in the 60s - with a different appearance and a modus operandi that fit his name: he stole hats, and the hat he wanted most of all was Batman's cowl. 

These two stories were adapted into episodes of Batman (1966). But the adaptation of the second story, "The Thirteenth Hat"/"Batman Stands Pat", adds a device that wasn't in the original: the Super Instant Mesmerizer, a device built into his hat that can hypnotize people.

The Mad Hatter made a couple more appearances in comics here and there, but hats were still his main focus. Then, almost twenty years later, the Mad Hatter appeared in Detective Comics #510 (November 1982), with a twist: apparently the Mad Hatter we had seen since the 50s, the one obsessed with hats, was NOT the one who stole the yacht club trophy in the 40s. But that original Mad Hatter was now back, and this time had an MO of his own: using technology to turn people into mindless zombies.

After that, mind control became a pretty regular part of Mad Hatter's repertoire, as seen in such examples as all of his appearances in Batman: The Animated Series and the Arkham games. And all (seemingly) because of that one change in the 60s!