Guicpert or Wigbert (died before 781) was the Abbot of Farfa for eleven months in 769–70 and probably also the Bishop of Rieti in 778. According to the twelfth-century chronicler of the abbey, Gregory of Catino, Wigbert was an Englishman and already a bishop when he convinced the dying Abbot Alan of Farfa to name him as his successor. From a twelfth-century perspective, Wigbert's accession was invalid because it was not in accordance with the Rule of Saint Benedict, although that rule was neither strictly nor uniformly enforced at Farfa in the eighth century. Nevertheless, the monks found Wigbert's rule a "tyranny" (in Gregory's words) and sought the king, Desiderius, to remove him and confirm their freedom to elect a successor, which he did.
Nothing is known about Wigbert between February 770 and April 778, but in the latter month the bishop of Rieti, named Guicpert in the source, received for the duration of his life the church of Saint Michael in Rieti from Hildeprand, Duke of Spoleto. This church had long been disputed between the dukes and the bishops, but the grant to Guicpert, which stated that the church was to revert to Farfa on his death, did not end the disputes. Guicpert's predecessor, Sinuald, had been bishop as late as March 777. By July 781, when a judicial decision of Charlemagne placed the church under the control of Farfa, Guicpert was dead.
- The identification of the abbot and the bishop–recipient of Saint Michael's in Rieti, based on Gregory's account, was first proposed by Carlrichard Brühl, "Chronologie und Urkunden der Herzöge von Spoleto im 8. Jahrhundert", Quellen und Forschungen aus italienischen Archiven und Bibliotheken 51 (1971) 1–92. "Guicpert" is a Lombardic spelling of the name "Wigbert".
- Marios Costambeys, Power and Patronage in the Early Medieval Italy: Local Society, Italian Politics, and the Abbey of Farfa, c.700–900 (Cambridge: 2007), 153. Alan is last mentioned alive in a charter of February 769. His death occurred on 9 March according to Gregory, cf. Costambeys, 153 n92.
- Costambeys, 153. For Wigbert's successor the monks chose a deacon of their own, Probatus.
- Costambeys, 98.
- For the dispute over Saint Michael's, cf. Costambeys, 96–98 and 226–31.