So, when DC Super-Stars #14 (May-June, 1977) rolled around, here was a chance to explore the beginnings of two villains, Gorilla Grodd and Doctor Light, (but with different heroes helping them get their start as shown on this Jim Aparo cover), as well as the origins of the master of duality.....Two-Face!
But, there are dangers with this as well....
G -- As In Guardians, Green Lantern And Gorilla Grodd
Here, it was suggested that it was Green Lantern that, unknowingly, brought Gorilla Grodd, Solovar and the rest of Gorilla City to Earth, as an extension of one of his missions to the planet of Calor in Green Lantern #1 (July-August, 1960).
Nice idea, but impractical, as around this time, Flash was first encountering the Trickster in his own magazine, having encountered Grodd a while ago (and Flash and Green Lantern were co-founders of the JLA before this as well, with Flash encountering Grodd before the JLA formed).
A later telling of the origin in Secret Origins #40 (May,1989) by Cary Bates, Greg Weisman, Carmine Infantino and Mike DeCarlo, had the gorillas here on Earth mutated in the later 1800s by a meteor that crashed to Earth, and constructed a device to shield their city from outsiders after an encounter with some explorers (until Barry Allen stumbled upon the city later).
Consistent with his usual origins, but oddly lacking Batman in this tale (though slightly tied to his appearances in Teen Titans with his "daughter", the Joker's Daughter/Harlequin...a crazed bit of continuity confusion herself!).
Secret Origins Special #1 (1989) by Mark Verheiden, Pat Broderick and Dick Giordano, explored Harvey's relationship with his wife, his becoming district attorney and working with Batman, and tragic turn into Two-Face (yet that he still loved his wife, Grace - called Gilda, pre-Crisis, as he had recently saved her as Two-Face from Dalton Perry, a criminal Dent had put away in jail).
Let There Be Dr. LightGreen Arrow, as well as the Teen Titans.
Problem arose with this story as well, as Katar Hol wasn't as available to be that Thanagarian police rookie (checking his extended origins in Brave and the Bold), and before the Crisis, the origin was amended to be "a Thanagarian police officer" who faced Dr. Light.
Secret Origins #37 (February, 1989) by Craig Boldman, Mike Parobeck and Ken Branch pull a Dr. Light of their own, stealing a thought from that past origin (but add to it and change it). Arthur worked at S.T.A.R. Labs, but was a failure, until he stole the light costume from scientist Jacob Farley, who invented the costume to be a hero like the JLA, but died before he got a chance to.
Brainiac and the Shark...and provide an interesting look at the thoughts of creators in the 1970s, trying to link various heroes and villains (and serve as a nice example now, of some of the differences between the DC Universe, from pre-Crisis to after the Crisis On Infinite Earths!).