"the knowledge of a widely recognized collection of the four Gospels which is used in worship is certainly substantially older than Irenaeus...Evidently Clement [of Alexandria] took it for granted that the collection of four Gospels was based on recognized church tradition and was unchallenged, since he does not have to defend it anywhere...Nevertheless the fact remains that it is utterly improbable that in this dark period, at a particular place or through a person or through the decision of a group or institution unknown to us, the four superscriptions of the Gospels, which had hitherto been circulating anonymously, suddenly came into being and, without leaving behind traces of earlier divergent titles, became established throughout the church. Let those who deny the great age and therefore basically the originality of the Gospel superscriptions in order to preserve their 'good' critical conscience, give a better explanation of the completely unanimous and relatively early attestation of these titles, their origin and the names of authors associated with them. Such an explanation has yet to be given, and it never will be. New Testament scholars persistently overlook basic facts and questions on the basis of old habits....Another comment on the name Matthew: apart from the first Gospel, to which he gives his name, Matthew plays no role in primitive Christianity. He appears only in the lists of apostles. He is only mentioned rather more frequently at a substantially later date in apocryphal writings on the basis of the unique success of the Gospel named after him. That makes it utterly improbable that the name of the apostle was attached to the Gospel only at a secondary stage, in the first decades of the second century, somewhere in the Roman empire, and that this essentially later nomenclature then established itself everywhere without opposition. How could people have arrived at this name for an anonymous Gospel in the second century, and how then would it have gained general recognition?...a recognized authority and not an anonymous Gentile Christian, i.e. a Mr. Nobody in the church, stood behind it [the gospel of Mark]...nothing has led research into the Gospels so astray as the romantic superstition involving anonymous theologically creative community collectives, which are supposed to have drafted whole writings." (Martin Hengel, The Four Gospels And The One Gospel Of Jesus Christ [Harrisburg, Pennsylvania: Trinity Press International, 2000], pp. 14, 16, 55, 71, 80-81)
"Marcion, on the other hand, you must know, ascribes no author to his Gospel, as if it could not be allowed him to affix a title to that from which it was no crime (in his eyes) to subvert the very body. And here I might now make a stand, and contend that a work ought not to be recognised, which holds not its head erect, which exhibits no consistency, which gives no promise of credibility from the fulness of its title and the just profession of its author." (Tertullian, Against Marcion, 4:2)
See also here and here.