The most original aliens I've seen in a while were the Elcor. Those guys were awesome. They should have had more of them. If they could have made those stupid elevators a little bigger, you could probably have one as an NPC. Imagine it, Shepard hiding behind a barrier with his/her little blue alien strumpet, pinned down by Krogan, saved suddenly by Manfred, the Elcor short-order chef, who bounds in from the side, his incredibly dense muscle mass allowing his limbs to smash through the Krogan armour, while he uses a back-mounted, brain-operated mass driver cannon to take out those pesky Geth snipers.