Terrorist could be quite a vague definition. Here are some ideas for sprite submission:
Spy vs. Spy stuff
Bio-suit creeping out of a barrel
Bio-suit creeping out of slime/poop/water
Ceiling walker (I was about to do that with one of my projects)
Suicidal bomber (lol)
Item bomb (not an item) expert
I wonder if there will be a sprite theme that is considered far-fetched or fictional (e.g. Demons!, 1920s-1990s Gangstas! [good idea here], Jailbreak!, Tyrants!, Dinosaurs!, Pop-Culture!, Emos!, Trees!, Memes!, Pac-Man!, Alien Invaders, Atari!, etc).