Cath Palug, also Cath Paluc, Cath Balug, Cath Balwg, Chapalu, Capalu, or Capalus, literally "Palug's cat", or maybe from the Welsh 'palug,' meaning 'clawing,' was a monstrous cat in French and Welsh legend. It was said to haunt the Isle of Anglesey, and to have killed and eaten nine score warriors. The Welsh Triads (Trioedd Ynys Prydain) make it the offspring of an enormous sow, Henwen, and claim that at birth it was thrown into the sea to drown. Surviving, it instead swam to Anglesey where the sons of Palug raised it, not realizing its deadly potential. Escaping, it wreaked havoc until slain by Cai (Sir Kay). In other versions, the victorious hero is King Arthur himself.
Another tradition of unknown origin associates it with the Mont du Chat in the Savoie region of France, near Lake Geneva, where Arthur was defeated by the Cat in a battle fought in a swamp near that mountain.