The Catholic Apostolic Church (CAC), also known as the Irvingian Church or Irvingite Church, is a denomination in the Restorationist branch of Christianity. It originated in Scotland around 1831 and later spread to Germany and the United States. The tradition to which the Catholic Apostolic Church belongs is sometimes referred to as Irvingism or the Irvingian movement after Edward Irving (1792–1834), a clergyman of the Church of Scotland credited with organising the movement.

A Christian denomination is a distinct religious body within Christianity that comprises all church congregations of the same kind, identifiable by traits such as a name, particular history, organization, leadership, theological doctrine, worship style and, sometimes, a founder. It is a secular and neutral term, generally used to denote any established Christian church. Unlike a cult or sect, a denomination is usually seen as part of the Christian religious mainstream. Most Christian denominations refer to themselves as churches, whereas some newer ones tend to interchangeably use the terms churches, assemblies, fellowships, etc. Divisions between one group and another are defined by authority and doctrine; issues such as the nature of Jesus, the authority of apostolic succession, biblical hermeneutics, theology, ecclesiology, eschatology, and papal primacy may separate one denomination from another. Groups of denominations—often sharing broadly similar beliefs, practices, and historical ties—are sometimes known as "branches of Christianity". These branches differ in many ways, especially through differences in practices and belief.