Christ Church Greyfriars, also known as Christ Church Newgate Street, was a church in Newgate Street, opposite St Paul's Cathedral in the City of London. Established as a monastic church in the thirteenth century, it became a parish church after the Dissolution of the Monasteries. Following its destruction in the Great Fire of London of 1666, it was rebuilt to the designs of Sir Christopher Wren. Except for the tower, the church was largely destroyed by bombing during the Second World War. The decision was made not to rebuild the church; the ruins are now a public garden.

In London, the Greyfriars was a Conventual Franciscan friary that existed from 1225 to 1538 on a site at the North-West of the City of London by Newgate in the parish of St Nicholas in the Shambles. It was the second Franciscan religious house to be founded in the country. The establishment included a conventual church that was one of the largest in London; a studium or regional university; and an extensive library of logical and theological texts. It was an important intellectual centre in the early fourteenth century, rivalled only by Oxford University in status. Members of the community at that time included William of Ockham, Walter Chatton and Adam Wodeham. It flourished in the fourteenth and fifteenth century but was dissolved in 1538 at the instigation of Henry VIII as part of the Dissolution of the Monasteries. Christ's Hospital was founded in the old conventual buildings, and the church was rebuilt completely by Sir Christopher Wren as Christ Church Greyfriars after the original church was almost completely destroyed in the Great Fire of London of 1666. The building now standing on the site, designed by Arup Group Limited, is currently occupied by Merrill Lynch.