So waaaay back when I was a very tiny Scape, I was massively into Red Dwarf. I used to be able to recite entire episodes from memory. I was the Dwarfer equivalent of hS, and I don't say that lightly. However, I wasn't able to keep up with the newer stuff, nor have I read the novelizations after Better Than Life. There's a lot of stuff I missed. But I'm still a huge fan.

Also Robot Wars, which is a robot fighting program that was once described as the world's first vegan blood sport. But you all know about that already. =]

First for me, in both creative output and time spent in the fandom, would have to be Pokémon. I tried copying the pictures on Pokémon cards and from a puzzle book I had in third grade, which eventually spiraled into me drawing gijinkas of the eeveelutions until I lost the folder I kept everything in on a field trip.

First thing I wrote for was actually The Giver, because an assignment in sixth grade had us writing possible epilogues.

The first thing I wrote for, though without knowing exactly what the concept of fanfiction was, was Warrior Cats. Just recently I found a tiny 2x3" notebook literally bedecked in glitter and sparkles containing a small sliver of the story I'd tried writing about my fan Clans, which I've actually sporked on the discord server a couple times.

The first thing that was knowingly fanfiction and posted online is a fic for Fire Emblem: Awakening, which I'm eventually going to get around to writing a mission for it.

---

edit for "oops, I forgot I have to italicize canons"

I mostly drew pictures of Pokemon from a handbook.

My sixth grade teacher did a literature unit on "Compare and contrast the Hero's Journey as seen in the Chronicles of Prydain and the Star Wars Trilogy" (this was back in '97-'98, so there was only one of them at the time), thereby introducing me to Star Wars. I discovered the Star Wars EU in the summer of '98 and stated writing fic for it later that year.

I don’t write fic, but the first fandom I really entered was Percy Jackson and the Olympians. I also didn’t really read fanfiction at all until I joined the PPC.

Sometimes, I can’t believe I only started reading Harry Potter this summer. Then again, I’m on the last book already, which is good. I’ll finally be able to read missions again!

Cloudy With a Chance of Meatballs (specifically the movies) was the first fandom I ever wrote fic (and RP) for; Person of Interest was the fandom I first properly engaged with after that, on forums and such.

And then there's Young Wizards, where I first started considering Tumblr (and then Slack thereafter, fortunately) to be a social media of interest...

(This would have been 2012/2013, btw. I came into the actual creative mode of fandom rather late, at least going by my generation's norms.)