Last night, I watched a documentary that featured a segment on chimpanzees. When you see the raw power, belligerence and sadism of male chimps - the sense they give off even in repose that in a split second they could explode into violence - it's hard to avoid the conclusion that they would make great orcs.
For me, goblins are like magpies. There is something cruel about the acquisitiveness and greed of a magpie. They are constantly on the look out for food, but they also give the impression that, all things considered, they also like to inflict misery and pain while doing so. (Eating carrion is good, but eating baby sparrows alive while listening to the impotent cries of their parents is better.)
Elves work well as cats. Slinky, inscrutable, lazy, and lacking in all empathy. There is no meaningful distinction between the aesthetically pleasing and the moral; murder is justified so long as it is done beautifully.
Dwarves are badgers. Industrious, gruff, reliant on tried-and-tested heuristics rather than creative flair.
Ogres are like elephant seals. They imbue strength, size, power and aggression with religious significance; one reaches fulfilment in both inflicting and receiving suffering and pain.
Halflings are beavers. Self-reliant and deriving pleasure only from a job well done.
Suggest your own.