Endless Mike
Illustrious
Another wacky but insanely overpowered Pre-Crisis DC villain. As you can tell by the title, this guy has a lot of different names (in fact, this thread actually covers two separate characters, but they both have the exact same powerset, so anything one of them did could easily be accomplished by the other). His appearance is also rather goofy-looking (even characters in-universe have said as much).
For an overall summary of what his deal is, we can look at his profile in Who's Who: The Definitive Directory of the DC Universe Vol 1 #5:
tl;dr - Joe Meach, a has-been stunt diver who resented Batman and Superman, got a job as a janitor at the Superman Museum, and when lightning struck a set of statuettes of the Legion of Super-Heroes, due to the peculiar way in which the statues were made, he was temporarily imbued with all of their powers. Later, an alien named Xan restored his powers, but Meach reformed at the last second and sacrificed himself to save Batman and Superman and defeat Xan. Xan later acquired the same powers for himself.
His appearances (save for reprints and cameos) were all from World's Finest vol 1, specifically, issues #142, #168, #283, and #284, so I really only had to cover 4 comics for this thread.
Here's some more detail on his origin, as it's pretty ridiculous:
I'm going to have to split this into multiple posts as apparently this forum won't let me make posts with more than 5 "pieces of media" (including links)...