One of the interesting things about the 1970s was how all sorts of different toy companies could get licenses for the same characters, although they'd have to produce different items. An excellent example of this is AHI (Azrak Hamway International) and Mego. Mego, of course, is best known for their line of 8" action figures, licensed from DC, Marvel, Star Trek, Planet of the Apes, and many others.
AHI also had many of the same licenses, but instead of producing action figures, they produced a lot of toys sold on cards at stores like Woolworth's, Kmart, and Kresge. So while Mego did Batman, Robin, Batgirl, villains, and Bat-vehicles for the figures, AHI produced smaller-scale Batmobiles, Batboats, Batplanes, Batcopters, paratroopers, and so forth. Now, AHI had to have noticed that Mego was making a lot of money selling their action figures, and when Mego produced their line of monster figures, they didn't use the Universal versions (apparently they thought the license was too expensive), so AHI decided to get the Universal license to produce the World's Greatest Super-Monsters, pretty much copying Mego's World's Greatest Super-Heroes packaging (now that I think of it, they may have been the first with the monster figures).
Anyway, after this, AHI was producing Planet of the Apes stuff (mostly copying things they'd done for other licenses, such as gyro-powered and friction motorcycles, paratroopers, helicopters, and other weird stuff, as well as some neat horse with wagon... but we'll get to these in the future), they must've wanted a piece of the action figure market, so they came up with their Action Apeman line! So far as I can tell, all the clothing for the Action Apemen was used previously for their generic soldier action figure line, Adventure Man (that was probably a reaction to Mego's Action Jackson as well as Hasbro's GI Joe), along with some original stuff.
Here's a picture of a loose Adventure Man, in case you're curious about it.
Some good pages about the Action Apemen are Megolike and Plaid Stallions. Someday, someone really needs to research AHI and produce a book about them, I think!
Oddly enough, these days it seems that the Action Apemen are more in demand with collectors than Mego's Planet of the Apes figures, given the prices I've seen on eBay! If you want to try to get one of these for yourself, this link will give you a listing of all the current Azrek-Hamway toys up for auction. One thing to be aware of, however: Not every seller is accurate with how they list these... some call them "Astro-Apes," and some even flat out call them Planet of the Apes figures!