The Church Fathers, Early Church Fathers, Christian Fathers, or Fathers of the Church were early and influential theologians, eminent Christian teachers and great bishops. Their scholarly works were used as a precedent for centuries to come. The term is used of writers and teachers of the Church, not necessarily "saints", though most are honoured as saints in the Roman Catholic, Eastern Orthodox, Oriental Orthodox, and Anglican Churches, as well as in some other Christian groups; notably, the heretics Origen and Tertullian are generally reckoned as Church Fathers.

The earliest Church Fathers, (within two generations of the Twelve apostles of Christ) are usually called the Apostolic Fathers since they were taught directly by the twelve. Important Apostolic Fathers include Clement of Rome,Ignatius of Antioch and Polycarp of Smyrna. In addition, the Didache and Shepherd of Hermas are usually placed among the writings of the Apostolic Fathers although their authors are unknown; like the works of Clement, Ignatius and Polycarp, they were first written in Koine Greek.

Mike Aquilina is a popular author working in the area of Church history, especially patristics, the study of the early Church Fathers.

He is the author or editor of more than thirty books, including The Fathers of the Church (2006); The Mass of the Early Christians (2007); The Resilient Church (2007); Living the Mysteries (2003); and What Catholics Believe (1999). His books have been translated into many languages, from Croatian and Portuguese to German and Braille. The Grail Code has appeared in ten languages since its publication in 2006.

Critics have praised Aquilina's work for making the Fathers accessible to non-academic readers: "Most scholars … study the paper trail — homilies, letters, teaching manuals, works of theological disputation … Aquilina loves the words, too. But he also finds the sermon in the stuff, the theology expressed in the little things that the first Christians left behind — fading murals on catacomb walls, pottery and dishware, pieces of coinage, ancient hymns and Mass prayers, common household items … The point is that for Aquilina, the little things matter — because they tell us big things about what Catholics believe and how they look at the world." Dr. John Grondelski said in the National Catholic Register: "Aquilina has made a vocation and career out of, in many ways, single-handedly popularizing patristics."