On video, he talked about really admiring Hillary, but I don't know that he was ever politically active at all. I don't think he was.
I think he leans left, but he did write some anti-commie comics in the '60s that disappoint the lefty kiddies when they read them today. Stan Lee is a guy I'd give a little wiggle room to, given how many brilliant characters he created and the wonderful, moral stories he wrote. "Most of the philosophy of my stories comes from the Bible," is close to what he has said before.