For the Ethiopian emperor, see Fasilides. For the martyr, see Basilides and Potamiana.

Basilides (Greek: Βασιλείδης) was an early Gnostic religious teacher in Alexandria, Egypt who taught from 117 to 138 AD, and claimed to have inherited his teachings from Matthew. He was a pupil of either Menander, or an interpreter of Peter named Glaucias. The Acts of the Disputation with Manes state that for a time he taught among the Persians. He is believed to have written over two dozen books of commentary on the Christian Gospel (now all lost) entitled Exegetica, making him one of the earliest Gospel commentators. Only fragments of his works are preserved that supplement the knowledge furnished by his opponents.