Croyland Abbey (occasionally spelled Crowland Abbey) is a parish church, formerly an abbey church in Crowland in the English county of Lincolnshire.

It was originally founded in the 8th century, and is dedicated to Saint Mary the Virgin, Saint Bartholomew and Saint Guthlac, the last of these having dwelt there as a hermit between 699 and 714. During the third quarter of the 10th century, Croyland came into the possession of the nobleman Thurketel, a relative of Osketel, Archbishop of York. Thurketel, a cleric, became abbot there and endowed the abbey with many estates. It is thought that, about this time, Croyland adopted the Benedictine rule.

Croyland is well known to historians as the probable home of the Croyland Chronicle, begun by one of its monks and continued by several other hands. In 1537, the abbot of Croyland wrote to Thomas Cromwell, sending him a gift of fish: "ryght mekely besechyng yow lordship favorablye to accepte the same fyshe, and to be gud and favorable lorde unto me and my pore house". Despite these representations, the abbey was dissolved in 1539.

Much of the abbey church survived for use by the parish, but large parts collapsed over the subsequent centuries. The present parish church is reduced to the north aisle of the old building, with ruins, including a fine west front, adjoining. One of the religious relics that the present church claims to contain is the skull of the 9th century Abbot Theodore which used to be on public display until it was stolen from its display case in 1982. The skull was later returned anonymously in 1999.

The abbey is also known for being the subject of a John Clare sonnet.