Apostolic Fathers by John Lightfoot

The Apostolic Fathers were either directly disciples of the Twelve Apostles of Jesus Christ, or were significantly influenced by them. Their writings, were popular in the early Christian church, but ultimately were not included in the canon of the New Testament. Many of the writings derive from the same time period and geographical location as other works of early Christian literature which came to be part of the New Testament.

These works include:

The Epistle to Diognetus

Letters attributed to Clement of Rome

The First Epistle of Clement
The Second Epistle of Clement

The Didache
The Epistle of Barnabas
Seven epistles attributed to Ignatius of Antioch
The Epistle of Polycarp
The Martyrdom of Polycarp
The Shepherd of Hermas