3&3/4" G.I. Joes, CDs, DVDs/Blu-Rays, books, video game magazines, Sports Illustrated magazines, NBA trading cards, tons of old VHS tapes with self-recorded sporting events on them. A lot of it is from my youth that I just never threw away. I'm sure it all pales in comparison to most of you since I sell a fair bit of my stuff off on the regular, check stuff out from the library for free, or just use services like Netflix, etc. instead of buying much anymore...
The last time I bought a Blu-Ray or DVD was about a year ago. And a CD? Even longer than that. Nonetheless, my video game collection is easily the largest of my collections.