Quartus (Greek: Κούαρτος, romanized: Kouartos) was an early Christian saint who is mentioned in the Bible.

According to church tradition, he is known as Quartus of Berytus[1] and is numbered among the Seventy Disciples.

[3] Quartus was born in the city of Athens, and was one of its wealthy and learned nobles.

Having received the grace of the Comforter on the day of Pentecost, he preached the gospel in many countries.

[2] The New American Standard Bible translates Romans 16:23 as follows: Gaius, host to me and to the whole church, greets you.