What was your first fandom, and are you still active in it? How did you participate in this fandom (discussion lists or communities, fan art, fanfiction, conventions, etc)? Link us to your favorite LJ journals/comms about this fandom.
It's cute how this question implies internet fandom without even meaning to. My first fandom was Star Wars, but I didn't know what fandom was then. I just sat around with my friends talking about Star Wars and snapping up any fiction we could about it.
Then came TNG, where I started going to cons and hearing rumors of this "fanfiction" thing. You had to buy it. On paper. It was expensive, and I couldn't afford it, but I knew of it.
And then...then came The X-Files. The be all and end all of fandom by nearly every measure. Why? Because of the internet. Philes were the first to have it and use it for fandom. And that was one hell of a ride.
Stargate SG-1 came next, then SGA, and Firefly. I'm active in Sherlock, Sanctuary, Farscape, Harry Potter, and many others, too. I'm a multi-fandom kind of girl. Variety is the spice of life and all that. My participation now is mostly fanfiction, but I'll play with art and forums sometimes.
But in the end, it comes down to five: Star Trek, Star Wars, Stargate, Firefly, and The X-Files. Always.