From Gurren Lagann of course. I've been trying to find a good picture where you can see the actual color, but his iris is usually just drawn as a dot or black circle.
That's what his eye's are. Although to be specific, his eyes are green as at the end of the series he has obtained spiral eyes.
He took an eyedropper on the one scene where he's standing with Kamina and it's like copper... Why couldn't they just draw his eyes out -_-
