Olegarius Bonestruga (from Germanic Oldegar, Latin: Ollegarius, Oligarius, Catalan: Oleguer, Spanish: Olegario; 1060 – 6 March 1137) was the Bishop of Barcelona from 1116 and Archbishop of Tarragona from 1118 until his death.

[2] As abbot of Saint-Ruf, Olegarius had mediated the Mediterranean alliance between the Republic of Pisa, Kingdom of Cagliari, County of Provence, and Barcelona against the Almoravid pirates based on the Balearic Islands, resulting in the expedition of 1113–15.

[2] In the Gesta triumphalla per Pisanos, facta de captione Hierusalem et civitatis Mayoricarum of the Pisan deacon Enric (not, as sometimes alleged, Lorenzo Verones), Olegarius' name is misspelled as Nogelarius or Nigelarius.

[3] Raymond Berenguer III named him bishop of Barcelona in 1116, and he was consecrated by Cardinal Boso of Sant'Anastasia in the cathedral of Maguelone in Occitania during the pontificate of Paschal II.

[4] At First Lateran he had been declared legate a latere over the Crusade in New Catalonia (i.e., the province of Tarragone) and began to take the title dispensator or rector of Tarragona.

[5] At Narbonne the council confirmed the interprovincial archconfraternity (confratrium) for the restoration of the church of Tarragona which Olegarius had established on a more local level a year earlier.

[18] On 14 March 1129 he ceded this secular authority in the district of Tarragona to Robert Bordet, with whom he had an antagonistic relationship, with the title of princeps Tarraconensis, effectively the archiepiscopate's vidame or defensor.

[15][19] In 1129 Olegarius was drawn into the Investiture Controversy then raging between Papacy and Empire and he returned to southern France to be with the pope in exile.

[21] He played an important role in December 1134 when, at Zaragoza, he brokered a peace between Ramiro II of Aragon and Alfonso VII of Castile.