The Group 13 network was a Jewish collaborationist organization in the Warsaw Ghetto during the German occupation of Poland in World War II. The rise and fall of the Group was likely a proxy for power struggles between various factions in the German military and bureaucracy, for their own financial benefit.

Abraham Gancwajch (1902–1943) was a prominent Nazi collaborator in the Warsaw Ghetto during the World War II occupation of Poland, and a Jewish kingpin of the ghetto underworld. Opinions about his ghetto activities are controversial, though modern research concludes unanimously that he was an informer and collaborator motivated chiefly by personal interest.