Frogs

For a whole minute, I thought the topic was about movies in which men would kill animals, leading to a police investigation and so on...

I really enjoyed Willard, especially because of the funeral home scene, Crispin Glover's acting and Laura Mulholland Drive Harring...
http://www.imdb.com/title/tt0310357/

It was a remake of that Willard, which I saw in my teens and made a good impression on me, probably for Ernest Borgnine's last scene...
http://www.imdb.com/title/tt0067991/

Ben looks like a sequel or an early remake centered on the rodent...

There's Monkey Shines that I liked a lot too, where the monkey's turned into a killer by some drug that has it read its owner's mind and desires. So it's not the animal's wish to start it all.
http://www.imdb.com/title/tt0095652/
The last scene was something.

Films with snakes I saw were rather bad.
The Birds, yes...
Does the Holy Grail rabbit count or is it too fake to be mentioned?

^ yeah...the only movies that I can recall with an animal killin' peoples is Cujo and Willard.

That rabbit fucked me up for life.