Stealth Moose
Umbrella Elite
It's really kind of jarring, to have this complex universe full of sentient aliens who are basically all cookie-cutters of each other.
All asari are nearly identical females. They all start life as warriors and bar dancers, then graduate to "have kids" stages, then get old and become the typical mystical old woman.
All volus are identical clumsy, narrow minded merchants who have no real faces and are trapped in a metaphorical pressure chamber. They rely on others to defend themselves.
All turians are apparently disgruntled, honor bound males. They can be evil, but if they are, it's because they are too self-important to realize their own pride and unsound logic.
All Quarians are faceless mechanical-inclined gypsies, who can't find a planet to live on even though humans who were relative newcomers to the universe are almost everywhere and are accepted with ease.
All elchor are lumbering gentle giants. That being said, elchor Spectre, ftw.
Really, all aliens are not complex at all beyond first glance. Compared to humans, they are "less genetically diverse", "less creative" (this is in response to why the turians, with the largest military might in known space and rigid, stoic battle doctrine could not overcome the humans in the First Contact War), "untrustworthy" (Although humans can be scum throughout the game, all batarians are thought to be liars and thieves, salarians all have that cold, sneaky scientist bent, asari are all temptresses, volus are all dumb merchants, etc.). Pretty much the only subversion to the stereotyping is the poetic Korgan on Illum.