If you don't believe it, check out this story of a vengeful bull in India:
The bull apparently kept a watch on frail Bhoop Narayan Prajapati, 65, and attacked him when he was having his morning tea, a day after he had thrown hot water on it for sitting in front of his hut. Prajapati ran inside his thatched hut to escape, but the bull followed him, pushed him to the ground twice and gored him.
Apparently there was a long history between this man and this bull: Six months earlier, he hit the animal with a stick and it retaliated, landing him in the hospital for a month.
And not only did the animal plot its revenge for months, it made sure its attack had been successful, and after he died, it returned to gloat:
The bull followed the man when he was being taken to a hospital and later appeared at the crematorium during his funeral.