Donercius or Donort is the second Bishop of Mortlach according to the list of the Aberdeen Registrum.Cosmo Innes, Registrum episcopatus Aberdonensis : ecclesie Cathedralis Aberdonensis regesta que extant in unum collecta, (Spalding and Maitland Clubs, 1845), vol. ii. p. 125 He is known only by name. Skene says that "Donercius has all the appearance of a fictitious name".William F. Skene, Celtic Scotland: A History of Ancient Alban, 3 Vols, 2nd ed., (Edinburgh, 1887), vol. ii. p. 380 Whether the name is fictitious or a corruption cannot be known from the existing evidence. His alleged predecessor Beóán is known to have been bishop in the reign of King Máel Coluim II of Scotland, so if Donercius really did exist, he was certainly bishop in the 11th century.See Beóán of Mortlach.
Notes
References Innes, Cosmo, Registrum episcopatus Aberdonensis : ecclesie Cathedralis Aberdonensis regesta que extant in unum collecta, 2 Vols, (Spalding and Maitland Clubs, 1845), Vol. II William Forbes Skene|Skene, William Forbes, Celtic Scotland: A History of Ancient Alban, 2nd ed., (Edinburgh, 1887), vol. ii