The Epistle of Barnabas is a Greek epistle written between AD 70 and 132. The complete text is preserved in the 4th-century Codex Sinaiticus, where it appears at the end of the New Testament, following the Book of Revelation and before the Shepherd of Hermas. For several centuries it was one of the "antilegomena" ("disputed") writings that some Christians looked on as sacred scripture, while others excluded them. Eusebius of Caesarea classified it with excluded texts. It is mentioned in a perhaps third-century list in the sixth-century Codex Claromontanus and in the later Stichometry of Nicephorus appended to the ninth-century Chronography of Nikephoros I of Constantinople. Some early Fathers of the Church ascribed it to the Barnabas who is mentioned in the Acts of the Apostles, but it is now generally attributed to an otherwise unknown early Christian teacher, although some scholars do defend the traditional attribution. It is distinct from the Gospel of Barnabas.

Barnabas, born Joseph (Ἰωσήφ) or Joses (Ἰωσής), was according to tradition an early Christian, one of the prominent Christian disciples in Jerusalem. According to Acts 4:36, Barnabas was a Cypriot Jew. Named an apostle in Acts 14:14, he and Paul the Apostle undertook missionary journeys together and defended Gentile converts against the Judaizers. They traveled together making more converts, and participated in the Council of Jerusalem. Barnabas and Paul successfully evangelized among the "God-fearing" Gentiles who attended synagogues in various Hellenized cities of Anatolia.