4th century BC Indian prince who ruled the region between the Hydaspes (Jhelum) and Acesines (Chenab) rivers at the time of Alexander III the Great's invasion (327-326 BC) of the Punjab. Unlike his neighbour, Ambhi, the king of Taxila (Taksashila), Porus resisted Alexander. But with his elephants and slow-moving infantry bunched, he was outmatched by Alexander's mobile cavalry and mounted archers in the battle of the Hydaspes. Impressed by his techniques and spirit, Alexander allowed him to retain his kingdom and perhaps even ceded some conquered areas to him. Thereafter a supporter of Alexander, Porus held the position of a Macedonian subordinate ruler when he was assassinated, sometime between 321 and 315 BC, by Eudamus' agents after the death of Alexander.

Not known in Indian sources, the name Porus has been conjecturally interpreted as standing for Paurava; i.e., the ruler of the Purus, a tribe known in that region from ancient Hindu Vedic times.