Phileas was a Christian bishop of Thmuis in Egypt during the late 3rd and early 4th centuries CE. He is primarily remembered as a martyr, executed during the Great Persecution under Emperor Diocletian. The traditional date for his death is 4 February, 306 CE. According to the contemporary historian Eusebius, Phileas was a man of wealth, education, and high social standing who chose to die for his faith. As a bishop, he was also involved in early church disputes, urging the schismatic leader Meletius to reconcile with the wider Christian community.

Only one of his writings survives. This is a pastoral letter, or epistle, written from prison to his congregation shortly before his execution, urging them to remain steadfast. The text is preserved only in fragments.

Phileas holds significance as a documented early Christian martyr. His death, recorded by Eusebius, became an important example of conviction for the early church. According to modern scholars, his surviving letter provides a valuable firsthand perspective on the theological mindset and pastoral concerns of a bishop facing persecution in early 4th-century Egypt, making it a useful primary source for this turbulent period.