So I saw the headlines in the news today about the Growing Pains actor who was missing and later found dead in Vancouver. I didn't think much about it since I'd never seen the show and didn't recognize the photo of him.
Then I read that his name was Andrew Koenig and he was the son of Walter Koenig, aka Pavel Chekov from classic Star Trek.
Then I read that not only was he on Star Trek: Deep Space Nine once, but that he also played Joker in the promotional short film, Batman: Dead End. This is way before Heath Ledger, of course, and some might say the definitive Joker portrayal -- certainly truer to the comic version than anything we've seen in feature films.