A backstabber is a slang term for somebody who speaks poorly or unkindly of another, usually a colleague, behind their back, or simply a traitor, who stabs your back (says or does bad things behind your back).
The Backstabber looks a little similar to the Penny Pincher, only with a more pointed and purple head, and the Pencil Pusher, because of their pointy head.
Mega Backstabber invasions occur on March 15, probably due to the historical betrayal on that day. This is because if someone is a Backstabber, he is kind to you when he speaks, but evil when you are not there. Therefore it is betrayal. These invasions are on the Ides of March.
(Coworker) backstabbing occurs to some degree in many workplaces. It consists of an employee doing something to another employee to get a "leg up" on the other employee. Strategies used for backstabbing include dishonesty, blame (or false accusation), discrediting others and taking credit for another’s work. Motives for backstabbing include disregarding others' rights in favor of one's own gain, self-image, management, revenge, jealousy and personal reasons
The Backstabber's head resembles a large knife.
The Backstabber's weakness is the Big Weight, because it dulls their cutting edge.
On the trading card, he is sharpening his head.
In the District Attorney's office, in the last room in each floor, there is a picture of the Backstabber trading card.
This cog's name is "Backstabber", but in-game, it's spelled, "Back Stabber".