User blog comment:Legionwrex/The most annoying enemy is the ..../@comment-737801-20100910041931

Most annoying huh. Well I'd have to agree with Tela for DLC enemies. Both the dialogue and the fight are very annoying to say the least

For the main game, I'd have to say either Scions or those every annoying combat drones. While you don't encounter the drones often, if you don't pay attention and shoot them when they appear, then they flank you, shock you, and get you out of cover. Annoying beyond belief.

Also since I'm currently on a run of ME I figured I should share that too. My most annoying enemies from ME would have to be Rachni Soldiers, Rachni Brood Warriors, or Geth Hoppers. All three are quite annoying, especially the last one with that very annoying, and deadly Assassination ability.