Cat - it was dark - right in front of my house. Next day my neighbor is outside calling here kitty kitty. Poor cat made it off the road into some woods before dying. Man did I feel bad about that.

I have also hit a snake, and a squirrel (squirrel survived).

Then there is the dog that chased me on my MTB and was biting at my ankles which I SHOULD have run over. Or should I have run over the owner standing there with leash in hand?