Deer Abbey was a Cistercian monastery in Buchan, Scotland. It was founded by 1219 AD with the patronage William Comyn, jure uxoris Earl of Buchan, who is also buried there. There was an earlier community of Scottish monks or priests. The notitiae on the margins of the Book of Deer record grants made to the Scottish religious community in the 12th century and a claim that it was founded by Saint Columba and Saint Drostan. The old religious community was probably absorbed by the new foundation. The history of the abbey after the 1210s is obscure until the 16th century, when it was beginning to be secularized. The abbey was turned into a secular lordship for Commendator Robert Keith II (becoming Lord Altrie) in 1587.
The Abbey was included in the lands obtained by Lord Pitfour and became part of the Pitfour estate in 1766. His son, the third laird built the 5 metres (16 ft) high enclosing wall in 1809 and used the grounds as an orchard. He also discovered some of the graves but did not disturb them. The fifth laird had the site cleared and used the stones from the Abbey building to have a mausoleum constructed in which to bury his daughter when she died aged 21 years in 1851. The only other person buried in the mausoleum was Ferguson's mother-in-law. The mausoleum was destroyed in the 1930s when the Abbey was transferred to Roman Catholic ownership and parts of it were used to build an entrance; however this was undertaken without disturbing the graves of Lady Langford and Ferguson's daughter, Eliza.
* Now in England, but at the time of its foundation, part of the Scottish kingdom of David I.
** Filiation from Mellifont Abbey in Ireland, founded 1142.
*** If this existed, it was shortly afterwards replaced by a Premonstratensian establishment.
**** In the line of filiation from Melrose (above).