Papias was a Greek Apostolic Father, Bishop of Hierapolis, and author who lived c. 60 – c. 135 AD. He wrote the Exposition of the Sayings of the Lord in five books.
There is much in-depth information in this article: The Synoptic Gospels in the Ancient Church: The Testimony to the Priority of the Gospel of Matthew. We have a brief introduction to papyrus from Tyndale Bible Dictionary. We have a lengthy apologetic article on Papias and the arguments from higher critics by F. David Farnell. This is followed by Papias' writings from two leading scholars on the Apostolic Fathers, Michael W. Holmes, and J. B. Lightfoot.