Famous Hunter

Kill 1000 enemies in total.
Self-explanatory; die frequently during the game and this should come towards the end of your first playthrough as all kills are recorded, even when you die; die infrequently and this will have to be unlocked during your hard playthrough: your statistics will carry over to your second playthrough via chapter select.

It's worth pointing out that any enemies you kill in Outbreak will also contribute towards this trophy.