Yes, the Joker, Batman’s most popular foe, was one of the first villains to be released by Mego in 1974!
Along with the Riddler, Penguin and Mr. Mxyzptlk, the Super-Foes were ready to fight the assembled Mego heroes. Joker, though, was a special case, having premiered (along with Catwoman – as the Cat, and Professor Hugo Strange) in Batman #1 (Spring, 1940, by Bill Finger and Bob Kane). Joker was suppose to die in his second appearance (he appeared TWICE in the first issue), but didn’t. And, has been a thorn in Batman’s side ever since. He was even the first of Batman’s foes to have his own magazine…nine issues from May 1975 to September-October 1976 (facing Green Arrow, and other Batman villains). And, better still, Joker was the only Mego figure to have a vehicle…the Jokermobile, as well as getting the honor (along with Batman, Robin and the Riddler) of being a special wave of figures, called the Fist Fighters, where with the push of a button, Joker can give Batman the old “Biff-Pow”!
With all this popularity, you’d think that the Joker would be in the forefront of Batman foes when Mattel released figures. It took a little time for Joker to be one of the DC Super Heroes figures (and, an oddly two-toned release the first time around…but that was because it was adapted from an earlier Batman line). Still, with Wave 10 of the DC Universe Classics, we got a more classic Joker! And, if that wasn’t enough fun…Joker also was released in a few two packs, one in a black suited variant (along with Harley Quinn, herself also released earlier in DC Universe Classics Wave 2), a more movie-style Heath Ledger looking Joker released along with Robin for Batman:Legacy Arkham City (and a Joker as police officer as seen in the Dark Knight, released along with a Batman figure), one of the people who faced Joker in his short series, the Creeper (who also borrowed from the Joker figure…look at that smile!) from Wave 16, and a more Golden Age Joker released with Wave 2 of the Batman:Legacy figures (as well as a Harley Quinn Arkham version in Wave 3). And, if you think this is the end of Joker figures (or articles on Mego and Mattel figures), the joke’s on you!

