User blog comment:Mictlantecuhtli/Melee Guide (Mass Effect 2)/@comment-3124011-20101022231950/@comment-737801-20101022232717

I don't remember the key on the PC, but on the 360 it is as follows. In Mass Effect, Shepard will auto-melee if they are close to an enemy. In Mass Effect 2, pressing B will result in a Melee attack, at any range.