The Talz Commando!
Specifically, the strong-version Talz Commandos found in the Power Station on Hoth.
These suckers have a couple evil things:
1.) Stealth Detect. It de-stealths you! Not only is that annoying, but the range on it is beyond the commando's normal aggro range. You think you're safe? Nope! What's even evil-er is that if you get de-stealthed, the commando and its entire group aggro you. Sheesh.
It also seems to cause aggro even when you aren't stealthed.
2.) Death by a thousand cuts. These guys have a serious lot of bleed (internal damage) DOTs. Both myself (lvl 40, Deception) and KV are at 10k health and one of these commandos almost killed us both, even with popping cooldowns.
Does anyone else hate these things?
I almost want more mobs like this (they are only in that one mission)... it makes things interesting/challenging when you can actually be detected (normally I just stealth to objective, grab it, stealth out), and when the mob seems custom-made to kill your class.