I had a Rainbow Brite character (Empathy/Energy) after the original one got generic'd. I then kept the name, while redesigning the outfit and the back-story. But everyone knew who it was supposed to be. Her classic 80's outfit still sat in the costume closet, and I used it whenever I was around trustworthy people. And I used it a LOT in the final months, figuring nothing would happen. It didn't.
I also had a Dr. Jenning villain (Gravity Control/Electric Blast). An ordinary astrophysicist who became possessed by a dark alien entity after a mishap with a prototype telescope. I don't think one person ever got the reference.
And of course, Tim the Enchanter, who never, ever got in any trouble. But I think everyone, even the suits, knows Monty Python wouldn't have given a damn.
All my other homage characters were from public domain.