Well, since Owlman took my original idea, I guess I'll go with Abin Sur, as he gave Hal his own ring in the comics, it stands to reason he'd appear first in animated or even live-action form.

Nope, it wasn't Sinestro. And how do you figure Abin Sur as a villain??

I think it was Evil Star, from that horrid 1960's rotating series of shorts. GL had an alien kid sidekick, too, if I recall correctly.

Solomon Grundy? That's all I got.

Ignatz gets it! Evil Star appeared in one of the Green Lantern segments of the Superman/Aquaman Hour of Adventure in 1967; a full 11 years before Sinestro and Solomon Grundy debuted on Challenge of the Superfriends!

Take it away, Iggy!

It's a sad case of speed-reading. I didn't see the word "villain" and was just going for the first GL to appear in a medium other then comicbooks.
And here I thought you were just being tricky when it was just a trick my eyes.

OK:

In one issue of the New Adventures of Superboy, a one-shot villain appeared who was clearly a counterpart/reference to a hero completely unrelated to Superboy-- and no reference was made to this fact. Who was the villain, and who was he a counterpart to?

The villian was Wall-Taan, and he was a counterpart to the evil one known as "John Boy". And he kept saying "good night" to people.

You are so close.

[No, you are not.]

If memory serves...wait, what were we talking about? Oh, yeah. I think the bad guy was named Doctor Chaos, and he was a counterpart to Doctor Fate.

Correct. He had a color-reversed version of Fate's costume (blue helmet and cloak) and yet this was never pointed out or made any kind of story element.

It was right after DC started the Order/Chaos thing that's been part of their cosmology ever since, when Dr Fate was dubbed and agent of the Lords of Order-- so I guess somebody (Cary Bates?) decided there ought to be an counterpart agent of the Lords of Chaos.

Yeah, it's a shame that story is most likely no longer in continuity. As I recall, Superboy threw the helmet (containing the Lord of Chaos) into space, where it just drifts endlessly, waiting to be found...

OK, new question. Name two Flash villains who appeared on television in live action before they appeared in animation. (Bonus points for naming the actors who played them.)

Trickster (Mark Hammil)
Weather Wizard?

Captain Cold was on the Superfriends, so unlikely he appeared in live action anytime before that.