A complete list of other races in all titles and movies.
Creep (AvP, AvP: War)
A dog owned by Cathie Dowes and Jame Roth. Machiko looked after it for a while when she stayed behind on Ryushi.
Daxter (AvP)
A dog that belonged to the Sheldon family on Ryushi.
Dominators (JLA vs Predtors)
The Dominion have noticed the large number of super-powered beings who originate from earth, and fear that one day the galaxy will be overrun by earthmen. Working on this theory, they form an alliance with other alien races in order to invade Earth and enslave it's populace. The Dominion work to co-ordinated the attack.
The Dominators had a theory that some humans contain a recessive genetic trait that will manifest a 'super power' when their life is endangered. The dormant gene is dubbed the 'Metagene', and all humans who derive their power from it are labeled 'Meta Humans'.
Martian Manhunter (JLA vs Predtors)
Real Name: J'onn J'onzz
Powers include flight, super-strength, telepathy, invisibility, and super-speed. Can freely alter his physical shape and density. Projects beams of energy through his eyes ("Martian vision"). Has a deep appreciation of Earth cultures and maintains numerous human identities around the world. Like all Martians, J'onn has an aversion to open flame.
In 2000, Martian Manhunter encounters the Yautja, alongside the JLA. These Yautja were DNA-enhanced by the Dominators to match their prey. Though they managed to behead him, he was able to reattach his head to his body. Once subdued, the Yautja blew open a hole in the JLA Watchtower (located on the moon) and allowed themselves to be sucked out into space rather than be captured.