In Doom 2016, you can find Collectibles. They are small action figures/figurines manufactured by the UAC. Thre are 26 Collectibles to find, with two in each level.
What The Collectibles Do
The Collectibles that you have found add cool demon/character models for you look at in the Collectibles screen. It gives you a chance to appreciate the awesome art in the game without the 'art' trying to kill you. Also, if you find all the Collectibles, you'll get an achievment called 'Every Nook and Cranny'.
Behind The Scenes
The VaultBoy Collectible is a nod to Fallout 4. The Keen Collectible looks like it's a nod to one of Id's Software previous games, Commander Keen. The American Hero Collectible is a nod to Captain America.