Mark the cousin of Barnabas
Mark the cousin of Barnabas is a character mentioned in the New Testament, usually identified with John Mark (and thus with Mark the Evangelist). The opinion that this Mark is a different Mark is found in the writings of Hippolytus of Rome who thought them to be separate people.
According to Hippolytus, in his work On the Seventy Apostles, Mark the Cousin of Barnabas (Col 4:10; Phlm 24) is distinct from John Mark (Acts 12:12, 25; 13:5, 13; 15: 37) and Mark the Evangelist (2 Tim 4:11). They all belonged to the Seventy Apostles of Christ (ranked #56, #65, and #14, respectively), who were sent out by Jesus to saturate Judea with the gospel not long before his crucifixion (Luke 10:1ff.). Hippolytus says that Mark the cousin of Barnabas was a leader of the apostolic church and the bishop of Apollonia. (There are three possible sites for this place: one in Greece, one in Thrace, and one in Cyrenaica.)
Paul mentioned Mark the Cousin of Barnabas explicitly in Colossians 4:10 (Bible Quotation from New American Standard Bible 1995 Update [NAU]):
Aristarchus, my fellow prisoner, sends you his greetings; and also Barnabas's cousin Mark (about whom you received instructions; if he comes to you, welcome him) (Col 4:10 NAU)
Paul mentioned the same Mark in Philemon 24, which was written at the same time, and carried by the same letter carrier (Tychicus, Col 4:7), to the receivers in the city of Colosse:
23 Epaphras, my fellow prisoner in Christ Jesus, greets you, 24 as do Mark, Aristarchus, Demas, Luke, my fellow workers. (Phm 1:23-24 NAU)