Hero of Alexandria was a Greek mathematician and engineer active in the 1st century CE. His precise dates are unknown, but his work is often placed around 62 CE based on an eclipse mentioned in his Dioptra. He worked in Alexandria, and his writings demonstrate extensive knowledge of predecessors like Ctesibius and Archimedes.

His major surviving treatises include Pneumatica, describing devices like the steam-powered aeolipile; Automata, on mechanical theaters; Mechanica, covering simple machines; Metrica, which contains Heron's formula for a triangle's area; Dioptra, on a surveying instrument; and Belopoeica, on catapults. The authorship of Catoptrica is sometimes questioned.

Hero is a seminal figure in the history of technology, systematically applying Hellenistic theory to practical engineering. His detailed accounts of complex devices showcase advanced mechanical knowledge, and his mathematical work remained influential for centuries. His writings were preserved in Byzantine and Arabic traditions, impacting later science.