We Are With You Zack Snyder
Adara
was a Green Lantern but on DC Wiki it says she her alignment is Bad.
Ahtier
has his alignment as Bad.
Laira Omoto
her alignment is Neutral.
I only listed her because that same site says that Thaal Sinestro is Neutral.
Batman Ninja more like Batman's Bizarre Adventure
We Are With You Zack Snyder
No that is the comics too the Green Lantern Corp is basically an intergalactic police force with Oa as home base.
edited 12th Apr '14 9:12:48 AM by Halberdier17
Batman Ninja more like Batman's Bizarre AdventureGreen Lantern rings don't normally choose people who are evil/villainous at the time. They are, after all, selecting for cops. A couple of times they've picked people who went bad later. Sinestro is the poster child, there was a one-shot villain Hal fought who was Aristocrats Are Evil who had somehow managed to hold on to his ring long after leaving the Corps, and Universo, a Legion of Superheroes villain, was eventually revealed to have been a Green Lantern before going bad.
edited 12th Apr '14 9:42:59 AM by SKJAM
Picking only on willpower/ability to overcome fear is a relatively recent development; GL rings have in the past shown the ability to consider character as well (up to the limits of their AI.) The other corps' rings have not shown quite the same ability to vet, but we do know for example that Star Sapphire rings strongly prefer female(ish) partners, even though men should be equally capable of harboring love.
I suspect a lot of questions can be answered by the fact the green lantern rings(excepting the starheart) were considered advanced technology requiring great will power to use before Grant Morrison introduced the emotional spectrum silliness and made green the color of willpower.
Before they were tools scouting for potential officers, now they are moths to willpower.
Buldogue's lawyerMaybe it was Geoff Johns but I though Grant Morrison was the one who turned Parallax into a giant fear bug and made yellow the color of fear. Maybe Geoff Johns was the one who took it overboard and made a whole spectrum that tied to Biblical events and the cycle of life?
Regardless, someone changed the yellow weakness from a flaw in the technology to a giant fear bug, beginning the general slide from scifi to fantasy.
Buldogue's lawyerIf I remember correctly, the original criteria for getting a Green Lantern ring were that one have a strong will, be couraeous, and be honest. The wording was something like, "Possess indomitable will, be completely honest, and without fear." The "without fear" bit has gotten quite a bit of play, I know, but the honesty bit seems to have been forgotten. True, though, nothing about mercy, compassion, or morality in there. One could possess all those qualities and be evil.
Whether one can steal a GL's ring and make it work seems to depend on the writer. I've seen stories where a villain has swiped GL's ring and GL just told the ring to come back to him and that was that. Other stories had it that someone could usurp a ring if that someone had a sufficiently strong will. Dunno what the rules might be now.

Okay, so the criteria to use a Green Lantern ring is
a) Willpower
b) Ability to overcome great fear
Neither of these are inherently heroic traits. Have there been villains with green power rings, other then Sinestro ? (I know he lost his early on).