Muahahahaha! Someone has already mentioned Dolphins in this thread, that makes my job easier.
In response to the idea that humanoid aliens are somehow unrealistic because 'aliens would evolve completely differently', I would like to point to Cetaceae, Ichthyosauriae and Selachii.
AKA Dolphins (and Whales and Porpoises), Ichthyosaurs and Sharks. Three groups of animals that all look fairly similar but that have massively different origins and physiologies. In fact, even though Cetaceans are more closely related to us Humans than they are to either Sharks or Ichtyosaurs, they look more similar to both than we do to some of our closest relatives (Tarsiers and Galagos, for instance). Convergent evolution is a thing so Humanoid aliens aren't any more or less unrealistic than any other shape, is what I'm saying.
So Stellaris, with it's mix of Anthropomorphs (what Stellaris calls humanoids, who look like slightly altered humans), Humanoids (who look like human-something hybrids) and xenomorphs (who look waaaaay different) does representation of the potential range of realistic alien forms well. Much better certainly than most Space games which either go fully humanoid or fully xenomorph for their aliens.