Gannicus or Cannicus was a Gallic slave, who together with the Thracian Spartacus, and the fellow Gauls Crixus, Oenomaus and Castus, became one of the leaders of rebel slaves during the Third Servile War (73-71 BC). In the winter of 71 BC, Gannicus, along with Castus, broke off from Spartacus, taking a large number of Celts and Germans with them, marking the second detachment of the rebellion.