Creepers

Creepers are aggressive mobs that spawn in dark areas as caves, and sneek up to the player, and will make the noise of a lit TNT fuse. If the player does not run away or kill them in time, they will explode and most of the environment around them will be destroyed, and if the player is near them when they explodes the player will get hurt.

Drops
Creepers, when killed drop 0-2 gunpowder when killed.