The Top 7... Game bad guys you didn't want to kill

Just as hostages can come to bond with their captors, so you end up liking GLADOS - the female-voiced computer in Portal, the Best Game Ever Made (TM). Guilt for killing her is prolonged because you have to do it a piece at a time. While she talks to you. Don't worry though, it's OK - she forgives you at the end via the medium of song. Er... time to play a different game, we reckon.

Above:You didn't really get emotionally attached to this thing, did you?