I love Vincent Price. My definition of fandom was probably too narrow, because I was excited to see his name in your comment, and that means I must be a fan.
Vincent Price, for sure, but that brings me to Old Time Radio, I guess that’s a fandom. The Saint, with Vincent Price, is a favorite. But, I also love Johnny Dollar, X Minus One, all the various Sherlock Holmes shows, and the few BBC Radio Doctor Who episodes I’ve heard are also great.
One thing about old time radio, though, is that I have to turn on this filter in my mind so that every sexist or racist bit of bullshit doesn’t pull me out of the story. It’s also necessary for golden age sci-fi. (EDIT: But it wasn’t strong enough to let me read Lovecraft, though perhaps I should try again.)
Plus, I also love Twilight Zone, but I’ve only watched the series a couple of times, so I’m a newb fan, I think.