"Why then do we call them Matthew, Mark, Luke, and John? Because sometime in the second century, when proto-orthodox Christians recognized the need for apostolic authorities, they attributed these books to apostles (Matthew and John) and close companions of apostles (Mark, the secretary of Peter; and Luke, the traveling companion of Paul). Most scholars today have abandoned these identifications,11 and recognize that the books were written by otherwise unknown but relatively well-educated Greek-speaking (and writing) Christians during the second half of the first century."
January 1, 1970
https://en.wikiquote.org/wiki/Historical_reliability_of_the_Gospels