Why do some cats bite? What causes cat anger?

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What causes cats to become so angry that they lose control of themselves and attack other cats or bite humans? I've been wondering this for awhile, cause my big cat, Big Man, is always jumping on our female cat and snarling and biting her fur and trying to hurt her. It's not a playful or loving thing, either! He is very vicious to the point that I have to keep them seperated all the time. I think he's mad about the litter box situation. Since we got a kitten he's been acting this way. Now whenever the kitten uses his litter box, he hunts down our other female cat, who is grown up and takes out his anger over the litter box on her Years ago, he would run at my foot and bite down and hold on with his teeth until he caused me to bleed. And, he did this everytime his litter box was used. He stopped once we got his litter box cleaned. I'm really at my wits end dealing with the behavior. Has your cat ever done strange things like that before or suddenly turned into a big mean cat after years of being adorable and sweet? How do you deal with litter box trouble when you have multiple cats? We're using clay cat litter. Could that be causing too much odor in the litter box? Would appreciate suggestions. Thanks!