Greyfriars is a Roman Catholic friary and parish located in East Oxford, which until 2008 was also a permanent private hall of the University of Oxford. Situated on the Iffley Road in East Oxford, it was one of the smallest constituent halls of the university. Its status as a permanent private hall (PPH) derived from the fact that it was governed by an outside institution (the Order of Friars Minor Capuchin, a Franciscan religious order), rather than by the fellows of the University as a constituent college is.

In 2007 the decision was made to close the hall, with students transferred to Regent's Park College. The buildings continue to host the friary which formerly co-existed with the hall.

Greyfriars has one of the most distinctive buildings in Oxford; it is the only flint-stone Norman-style building in the city, and its green spire is prominent along the Iffley Road and from the university's Roger Bannister running track.

The original Greyfriars church and friary was founded by the Franciscans in 1224. The friars had a long and esteemed history in Oxford, listing many famous alumni, including the English statesman, Robert Grosseteste, also a theologian and Bishop of Lincoln, who became head of Greyfriars, Master of the School of Oxford from 1208, and the first Chancellor of the University of Oxford. In 1517, the order divided into two branches. The friars who had been living in city-convents, ministering there and teaching in universities became known as "Conventuals"; while the friars who preferred a more eremitical life became known as "Observants". (The Capuchins developed in 1528.) The friaries were suppressed during the Reformation in the 16th century.

In 1905, the Capuchin branch of the order established a friary, known as St Anselm's, which was recognised by the university as a house of studies in 1910. The Church of St Edmund and St Frideswide on Iffley Road was established in 1911 as a chapel of ease to the Jesuit Church of St Aloysius; the architect was Benedict Williamson. In 1928, the Jesuits handed it over to the Capuchins, who then built the friary.

In 1919, the friars moved to the current site on the Iffley Road – first naming it Grosseteste House after the first head of the original Greyfriars – and on completion of the present building in 1930, the name of Greyfriars was adopted once more. The status of permanent private hall was conferred upon Greyfriars by the university in 1957 and surrendered in 2008.

In October 2007, the order announced its intention to withdraw from its ministry as a permanent private hall of the university, for financial and personnel reasons. Given the age of the building and the reduced number of friars, the cost of maintenance, rehabilitation, and staffing would be unsustainable for the province, and negatively impact other ministries elsewhere. Arrangements were made to transfer all students and prospective applicants so interested to Regent's Park College. The decision aroused considerable controversy; substantial proposals by the fellows for the continuation of Greyfriars were considered by the Governing Body. The university eventually indicated that the friars' licence to run Greyfriars as a PPH would not be transferred to any other body, and the hall closed in June 2008, despite a last-minute attempt to save the hall by the Holy See.

It may seem strange that the Greyfriars students did not migrate to St Benet's Hall (the Benedictine PPH) or Blackfriars Hall (the Dominican PPH). However, Greyfriars had some years earlier admitted female students, and at that time neither of these other Catholic PPHs had done so. Regent's Park welcomed the Greyfriars students and the migration is commemorated by a plaque at Regent's Park. The latter announced in 2018 that it would be seeking donations to fund a Greyfriars Scholarship at Regent's. St Benet's Hall closed in 2022