Publius Cornelius Cossus was a consular tribune of the Roman Republic in 415 BC. Cornelius belonged to the Cornelia gens, one of the early Republics most influential patrician families which branch, the Cossi, rose to prominence during the late 5th century BC. Cornelius was the son of a Aulus Cornelius, possibly the quaestor Aulus Cornelius in 459, the famous Aulus Cornelius Cossus, consul in 428 BC, or another otherwise unattested Aulus Cornelius.