Philo of Byzantium was a Greek engineer and writer on mechanical technology active during the Hellenistic period, most likely in the late third to early second century BCE. He is often associated with Byzantium but may have worked in Alexandria. As a practical mechanician, he applied mathematical principles to the construction of devices.

His major work is the Mechanike syntaxis (Mechanical Collection), a nine-part compilation covering mechanics and technology. Only portions survive. Book 4, the Belopoeica on artillery, is preserved in Greek. Book 5, the Pneumatica, survives in Arabic and Latin translations. Book 8 exists fragmentarily. The lost sections treated topics from harbor building to automata.

Philo is a crucial figure in the history of ancient technology. His Mechanical Collection synthesizes Hellenistic engineering knowledge, providing mathematically-based formulas for artillery and describing pneumatic devices. His work influenced later writers like Hero of Alexandria and, through Arabic translations, medieval Islamic and European technology.