Blessed Thiemo (Thimo, also Dietmar, Theodinarus) (about 1040 – 28 September 1101/02) was a martyr and Archbishop of Salzburg from 1090 until his death.
A scion of the Bavarian comital House of Vornbach (Formbach), Thiemo reportedly was a talented painter and sculptor. He entered the Benedictine abbey of Niederaltaich and in 1077 became abbot of St. Peter's in Salzburg. Under Archbishop Gebhard he was caught up in the Investiture Controversy, as a papal supporter in opposition to German king Henry IV. In 1081 he went into exile, at first to Mönchsdeggingen and Hirsau, later to Admont. In 1086 he was able to return to Salzburg, together with Archbishop Gebhard, whom he succeeded in 1090, confirmed by Pope Urban II.
In 1095 Archbishop Thiemo attended the Council of Piacenza, while the domestic conflict with antibishop Berthold of Moosburg, who had been appointed by Henry IV, continued. He was defeated by Berthold's troops in 1097 and escaped to Carinthia, where he was arrested at Friesach by the forces of the Gurk bishop. Freed by a loyal monk, Thiemo found a refuge in the diocese of befriended Bishop Gebhard of Constance at Petershausen Abbey.
In 1101 Thiemo decided to join Duke William IX of Aquitaine on his crusade to Palestine and did not return. Several traditions concerning his death exist. He may have been taken captive by the Seljuqs of Rûm at Ereğli (Heraclea) in Anatolia in September 1101 or was imprisoned by the Fatimid Caliphate at Ashkelon in the following year. His martyrdom is described being tortured and killed by pulling the intestines out of his body with a spindle.
He was never formally canonized but is commemorated as a martyr by the Catholic Church. His name day is 28 September.