Lydia of Thyatira (Greek: Λυδία) is a woman mentioned in the New Testament who is regarded as the first documented convert to Christianity in Europe.

[3] She was evidently a well-to-do agent of a purple-dye firm in Thyatira, a city southeast of Pergamum and approximately 40 miles (64 km) inland, across the Aegean Sea from Athens.

Paul, Silas and Timothy were traveling through the region of Philippi when they encounter "a reputable businesswoman and possibly a widow... [who] was a righteous Gentile or 'God-fearer' attracted to Judaism".

[6] "Thyatira in the province of Lydia (located in what is now western Turkey) was famous for the red [variety of purple] dye".

[1] Lydia of Thyatira is most known as a "seller" or merchant of purple cloth, which is the likely reason for the Catholic Church naming her "patroness of dyers."

[5] Ascough cites other examples of noble women named Lydia from the first or second centuries,[8] so it is unlikely that she was actually a slave or servant.

[5] Lydia's evident social power exemplified by her control of a household and ownership of a house (which she offered to St. Paul and his companions) indicates that she was most likely a free woman and possibly a widow.

[10] Many Christian denominations recognize Lydia of Thyatira as a saint, though her feast day varies greatly.

A modern baptistry is located on the traditional site in Krynides where Lydia was baptized by St. Paul near Philippi as well.