Thief Creepers are made up by me. If anyone wants to make this into a mod or use for an animation, please give credit and/or give a link to this page, but permission is granted.

If Thief Creepers were implemented, their behavior would be:

Unlike most creepers, thief creepers are passive mobs and, when attacked, flee, not fight. They carry chests on their heads and when a valuable block is within 16 blocks, they will first get to it. They can make mini-explosions if any blocks are in the way. They make a mini-explosions when near the valuable to turn the item into a drop, then they pick it up, and run away. Theif creepers are twice as fast as the player and so the player will have to sprint, fly, or use potions of swiftness to keep up. They have the same health as regular creepers. When no valuables are nearby or they are not being pursued by a player, they will seek other creepers and give the valuables away. When killed, they drop 0-3 gunpowder, 0-1 chests, and all the items they haven't given away yet.

Items theif creepers consider "valuable" are: Iron ore, Iron blocks, Gold ore, Gold blocks, Diamond ore, Diamond blocks, Blocks of lapis, Redstone ore and redstone blocks.