Theodoric the Monk (Latin: Theodoricus monachus; also Tjodrik munk; in Old Norse his name was most likely Þórir) was a 12th century Norwegian Benedictine monk, perhaps at the Nidarholm Abbey. He may be identical with either Bishop Tore at Hamar or Archbishop Tore Gudmundsson, who both went under the name Theodoricus in the Abbey of St. Victor, Paris.[1]
Theodoric wrote a Latin history of the kings of Norway, Historia de Antiquitate Regum Norwagiensium sometime between 1177 and 1188. The work covers Norwegian history from the reign of the 9th century Haraldr hárfagri up to the death of Sigurðr Jórsalafari in 1130. Theodoric states that he considered it "utterly unfitting to record for posterity the crimes, killings, perjuries, parricides, desecrations of holy places, the contempt for God, the plundering no less of the clergy than of the whole people, the abductions of women and other abominations which it would take long to enumerate"[2] which followed the death of Sigurðr (see Civil war era in Norway).
Theodoric's work is one of the Norwegian synoptics, the oldest preserved kings' sagas. The others are Historia Norwegie and Ágrip af Nóregskonungasögum. Theodoric relied heavily on Icelandic sources, possibly including the Oldest Saga of St. Olaf and Oddr Snorrason's Óláfs saga Tryggvasonar.