It's rumored that Martin Abrams got the idea for the toyline after going to a marathon of Ape films with his son, the resulting sales of Mego Apes merchandise in 1974 reached $16 million.
Noticeably absent from the line is a Taylor doll, Neal Kublan explains why there was no Chuck Heston doll "Because we would have had to pay (Heston), he had that kind of a contract, so we just used a character; the helmet comes from Action Jackson, the jumpsuit too. We never made a new tool if we didn't have to."
The Astronaut head is an early figure used in test shots as Dinah Mite's boyfriend Don (Superman later took that role).
Note the prototype cards in these shots