I think one of the closest "evil races" I've heard of was the Mongols. They massacred entire towns apparently for the joy of it, they didn't actually take anything useful (except a few of the younger women), and they seemed to delight in spreading exactly the attitude you state, making themselves hated for generations. They didn't even seem to care much for their own, having a "if you can't keep up we'll kill you so you don't slow us down" policy, and behaving much like army ants (if the river is too deep, keep piling more people into it and ride over the top).

And then there's the dehumanisation factor. If people can be convinced that "the enemy" (who might be "everyone not 'us'") are not really human, then killing them is no worse than killing animals or insects (how many people really think twice about swatting a wasp?). In that situation, they people may have been infected with an evil idea ("He isn't really human, he's an animal") but they aren't necessarily evil for acting on that. As in your Alien and Predator examples, they don't recognise humans as anything apart from food and a convenient way to reproduce.

(No, I don't think that there is an absolute virtue or an absolute vice, or at least not one that we will ever be able to say is definitely one. What looks like courage may be a failure to grasp the danger, loyalty may be an imposed guilt, etc., we just can't know without being telepathic. Is a mother cat 'loyal' to her kittens when she defends them? Is she being 'courageous' when she faces down a large dog to defend them? Do those things even have any meaning? I know that a lot of 'heroes' have said that they didn't think of it at the time, they just did what needed to be done, were they 'courageous'? No, I'm not expecting answers, I don't believe that there can be any absolute answers to that, it's the point...)