Introduced as "the most horrible group of criminals in all history", they are a group of 13 thieves who specialize in very difficult targets. Unlike most other thieves, they generally don't rely on subtle strategy or minuted actions; perpetually reenacting the Gordian Knot parable, they prefer to resort to brute force. Loads and loads of brute force. Which is why they get such a reputation: They are less famous for what they steal than for the hundreds of people they kill in the process. In fact, as they already steal all the common objects they need on a daily basis, they have very little interest in the luxury items they target, and seem to chose them mostly because they know these items will be heavily guarded. Indeed, most of the members seem to be in specifically for the carnage.
They have a peculiar organization, being villainous True Companions of Ubermenschen (this doesn't go without the occasional internal frictions, though they have strict rules about settling those), and while they have a leader, the survival of individual members (including the leader) is not a priority; the survival of the group as the whole is. If a member dies, they simply get replaced.
Several of the members come from Meteor City, officially a gigantic landfill, less officially an autonomous city inhabited by millions of Unpersons, even less officially a Mafia-subsidized breeding-ground for anonymous hitmen.
The group is often referred to as "The Spider", because of the 12-legged spider tattoos that mark their membership.