For me, Bionicle should be the very obvious top of the list.
![:D :D](https://www.gangoffive.net/Smileys/gof/e7000984.gif)
My Little Pony: Friendship is Magic and its spinoff series Equestria Girls are also high up there for me.
![:yes :yes](https://www.gangoffive.net/Smileys/gof/in-yes.gif)
Also among my top fandoms are any of Lego's original themes, such as the Lego Movie franchise and the Ninjago series (one of my goals for the new year is to finally actually watch some episodes of that TV series)
Below all of that, I suppose playing all of those Lego video games over the last three years has influenced me enough to have at least a mild interest in various other major fandoms:
Star Wars
DC Comics
Marvel
Doctor Who
Back to the Future
Jurassic Park
Indiana Jones
Pirates of the Caribbean
The Incredibles (and other Pixar movies)
Lord of the Rings
Harry Potter
Those last two in particular are ones that I otherwise would've never cared much for at all, if not for the Lego video games that allowed me to gain some familiarity with them.
And although it's not related to Lego like the others, I'm also going to include Star Trek.
Oh, and if it's okay to include nonfiction series as well, I'm definitely going to have to throw in MythBusters (and probably BattleBots, too).