Mouse (noun; excessively timid and shy)
Pig (noun; either greedy with food or given to unrestrained words/behaviour)
Snake (noun: sneaky, conniving)
Crow (verb; continually rattle on about any unpopular subject)
Rat (verb; expose bad behaviour to higher authority)
Horse (noun; strong or has great stamina for hard work)
Bear (noun; dangerously unpleasant when angry)
Donkey (aka jackass; noun; careless about insulting others or causing trouble for the sake of it)
Bull (noun; careless and reckless to the point of causing damage)
There are many others, of course, some of which I won't put in print. Most that I considered are negative.