Slayer of Beasts

Slayer of Beasts is an Fallout 3 achievement on Xbox 360 and PC and a trophy on PlayStation 3.

Details
It is granted for killing 300 creatures. A creature is anything living that isn't human or isn't a non-player character. Robots, Radscorpions, Super Mutants, Bloatflies, radroaches, trogs, and Feral Ghouls all count toward this achievement. A list of "creatures" that can go into the count can be found here.