Order of Taraka
The Order of Taraka was a society of assassins founded around the time of King Solomon. Its members are extremely diverse, including humans, vampires, demons, and other creatures. Each member has no mission but to find and eliminate his/her/its quarry. Further, when one member is killed, another immediately takes up their mission. Members of the Order are identified by the rings they wear on their fingers.
The Order was hired by Spike to destroy Buffy Summers, the Slayer- the three assigned to the task were the human Patrice, who disguised herself as a police officer, the giant Octarus, and the gestalt of insects known as Mister Pfister, who pretended to be a salesman. Buffy destroyed all three, and the contract was later called off.