Your boss or line-manager. A good shit-buffer will protect your from all the shit raining down from senior levels of management. They will stop you from being pulled into random projects and protect you from all the politics so you can just get on and do your job without unnecessary stress.
A Head Buffer is the professional title of an individual who is employed to shine the bell end of a cock, which in turn buffs out any imperfections thus earning them the title.
"Man, Thomas is so good at his job, he must be the best Head Buffer around."
"Yea he's good but he's not the King Head Buffer"
A Comfort Buffer is a friend-zoned person who is used as a comfort, for someone who is trying to fix a current / ex relationship. The buffer is simply there to provide friendship comfort and may not continue their friendship if a relationship is fixed.