Bruce Timm on “The Terror Beyond” (circa 2004): “That’s our backward homage to the Defenders. It was one of those weird things where I had pitched a story that had an odd two-part structure. We wanted to bring Aquaman back, because we really liked the Aquaman episode from the first season, and I was toying with this idea of H.P. Lovecraft—a lot of his ‘Cthulhu Mythos’ deities are water-based. So that gave me a hook, and I thought, ‘It could be interesting if it was a Lovecraftian monster attacking Atlantis and the Justice League helps Aquaman defeat the monster.’ Then I thought, ‘That takes care of the aquatic side of the Lovecraftian theme, but then there’s the sorcerous side of it.’ So the original story was, at the end of Part One, they seemingly defeat the monster, they fly back towards Metropolis, and they get back home and realize that whatever they had done to defeat the monster has unleashed a portal and now there’s a full-scale invasion of our dimension from these Lovecraftian beasties. Part Two would not have [had] Aquaman in it, but would have Dr. Fate, just to keep our guest stars down to a minimum per episode.

“The writers totally did not like the story. They thought the gimmick of it—the fact that it was two seemingly unrelated stories that are connected by a little thread in the cliffhanger—they thought it was a little odd; they just couldn’t see the story. So I kind of gave up on that, but then I mentioned, ‘You know, we’ve got Aquaman here and Dr. Fate; we’ve basically got two-thirds of a DC Comics alternate universe version of the Defenders.’ Little light bulbs started going off over everybody’s heads. I said, ‘All we need now is the DC equivalent of the Hulk.’ Somebody mentioned Grundy and it all went from there. It was a weird, fun thing (courtesy of Modern Masters, Volume Three: Bruce Timm).”