A Za'tarc is a being who has been mentally reprogrammed to, when exposed to a trigger, kill another being and then kill themselves. They are often used to assassinate people in places where an Ashrak would not be able to enter, such as at heavily guarded secret meetings between enemies of the Goa'uld. Someone who is going to be present at the time but is easier to reach than the target for assassination will be kidnapped, reprogrammed, then sent back to their world with no memory of the experience but upon seeing the target will lose control of themselves and kill them both. (SG1: "Divide and Conquer", "Allegiance")