Valentinus, also spelled Valentinius (circa 100-160), was an early Christian Gnostic theologian born in the Nile delta and educated in Alexandria. He traveled to Rome and when another man was chosen bishop over him, Valentinus broke away and founded his own theological group. Only fragments of his writings survive, mostly in quotations by his critics.

Valentinus is the first of a series of religious thinkers the narrator cites in discussing the ticklish topic of mind versus body, and the extent to which God might be like human beings in their bodily functions.

This Valentinus is not the same person as the martyred saint or saints from whom Valentine’s Day derives its name, nor a Valentinus who led a Roman rebellion in the fourth century, nor again the Valentine who was pope for 30-40 days in 827.