I suppose Fan Club may not be the best term. Fan Clubs are something you mail into to get merchandise. I'm specifically referring to stuff like IMDB actors pages, or sub-Reddits for celebrities. Any group that gets together for the express purpose of obsessing over an individual.
Ever read some of the actor forums on IMDB? It's terrifying. The constant reference to people they don't know by the first name only, the public statements of sixual fantasy (also present on a few forums for younger actors as well), and so on. What are your favorite outfits they've worn? What's your favorite line in all of their movies? Let's lobby for an Oscar for this crap film because this guy/girl has a bit part as the guy who works the register at the coffee shop in this one scene. Let's manufacture rivalries with people because their middle name has one letter in common!
I've been on the internet for a long time, and it seems like this has gradually gotten worse over the years. These day, most of these read like a stalker's convention. It seems like if they were actual meetings with actual people in an actual location, the free coffee would be roofied by default. Am I nuts? Has it always been this way, or has the amount of hokerrs on the internet reached critical mass?