Udo of Nellenburg (c. 1030/5–11 November 1078) was the Archbishop of Trier from 1066 until 1078.

Udo was born in Tübingen in Swabia as the eldest son of Count Eberhard of Nellenburg. After the murder of the foreign bishop Cuno I of Pfullingen in early June 1066, the cathedral chapter elected Udo, one of their members, the new archbishop. In 1067 he received priestly consecration. Udo became in the anti-Simony campaign of Pope Alexander II. Beginning in 1075 he became involved in the Investiture Controversy between Pope Gregory VII and Emperor Henry IV, and was looked on as mediator in the dispute. He was however unable to maintain peace, but still worked to resolve the dispute. In August 1077 he negotiated a fair reconciliation and maintained his position with Rome. In March 1078 he received a letter from the Pope asking him to work further for the reestablishment of peace. He died in 1078 besieging Tübingen]] with the Emperor's army, and was eventually buried in the Cathedral of Trier.

Preceded by:

Udo of Nellenburg

Succeeded by:

Cuno I of Pfullingen Archbishop of Trier
1066 - 1078
Engelbert of Rothenburg