|Head||Bishop of Aberdeen|
|Archdeacon(s)||Archdeacon of Aberdeen|
|Known rural deans||Aberdeen, Boyne, Buchan, (Formantine), Garioch, Mar|
|First attestation||c. 1012 (for Mortlach)|
1131 x 1132 (for Aberdeen)
|Metropolitan before 1472||None|
|Metropolitan after 1492||Archbishop of St Andrews|
|Cathedral||St Machar's Cathedral|
|Native dedication||Saint Machar|
|Catholic successor||Resurrected 4 March 1878 (see Roman Catholic Diocese of Aberdeen)|
|Episcopal successor||Diocese of Aberdeen and Orkney|
Diocese of Aberdeen was one of the 13 (14, after 1633) dioceses of the Scottish church, before the abolition of the episcopacy in 1689.
A see was founded in 1063 at Mortlach by Blessed Beyn. The earliest mention of the See of Aberdeen is in the charter of the foundation, by the Earl of Buchan, of the Church of Deer (c. 1152), which is witnessed by Nectan, Bishop of Aberdeen. The first ecclesiastical record may be found in a Papal Bull of Pope Adrian IV (1157), confirming to Bishop Edward the churches of Aberdeen and Saint Machar, with the town of Old Aberdeen and other lands.
The granite cathedral was built between 1272 and 1277. Bishop Thomas Spence founded a Franciscan house in 1480, and King's College was founded at Old Aberdeen by Bishop Elphinstone, for eight prebendaries, chapter, sacristan, organist, and six choristers, in 1505. The see was transferred to Old Aberdeen about 1125 and continued there until 1577, having had in that time a list of twenty-nine bishops.
The Scottish Reformation was formalised in 1560 when, by act of Parliament, papal authority and many other Catholic beliefs were rejected, resulting in the church in Scotland being separated from the Holy See. In 1582, the Church of Scotland rejected episcopal government and adopted a Presbyterian model. Two years later, in 1584, King James VI tried to bring the Church of Scotland under royal control by appointing two bishops; this met vigorous opposition and he was forced to concede that the General Assembly should continue to run church affairs. However, after acceding to the English throne in 1603, James VI stopped the General Assembly from meeting and increased the number of Scottish bishops. In 1637, the introduction of an English-style Prayer Book into the Scottish church saw riots break out across Scotland, resulting in the abolition of the episcopacy in 1638. However, with the Restoration of the monarchy in 1660, episcopacy was reintroduced. Following the Glorious Revolution of 1689, the Scottish bishops refused to swear allegiance to William of Orange leading to the abolition of the episcopacy and the Presbyterian form of church government being re-established once more.
In 1653, Scottish Catholics came under the Prefecture Apostolic of Scotland, which was elevated to the Vicariate Apostolic of Scotland in 1694. That same year the Scottish Catholic clergy were incorporated into a missionary body by the Congregation of the Propaganda. As growth took place, Scotland was divided into two Vicariate Apostolics in 1727: the Highland District (including Aberdeen) and the Lowland District. The Highland District was renamed the Northern District in 1827 and, in 1878, it became the Roman Catholic Diocese of Aberdeen.
On 4 March 1878 Pope Leo XIII restored the Catholic hierarchy of Scotland by proclamation of the Bull Ex supremo Apostolatus apice and Vicar-Apostolic John MacDonald was translated to the restored See of Aberdeen as its first post Reformation bishop.
The Bull made Aberdeen one of the four suffragan sees of the Archbishopric of St. Andrews and Edinburgh, and defined as its territory "the counties of Aberdeen, Kincardine, Banff, Elgin or Moray, Nairn, Ross (except Lewis in the Hebrides), Cromarty, Sutherland, Caithness, the Orkney and Shetland Islands, and that portion of Inverness which lies to the north of a straight line drawn from the most northerly point of Loch Luing to the eastern boundary of the said county of Inverness, where the counties of Aberdeen and Banff join."