Armentarius (Spanish: Armentario) was the Bishop of Mondoñedo, when its seat was still at Dumium, from at least 984 until his death sometime between 1018 and 1025. Armentarius is first recorded as bishop on 24 April 984. His predecessor, since as early as 977 perhaps, was , whose loss of his see cannot be dated more precisely. On 29 September 985 he subscribed a charter of Vermudo II of León privileging the Abbey of Celanova. On 1 February 1007, as bishop of Mondoñedo, he confirmed the ruling of Alfonso V of León ordering the return of various properties belonging to the Abbey of Celanova that had been illegally occupied by certain foreigners in the days of Vermudo II. This ruling was also confirmed by Arias Peláez. On 22 August Alfonso V also ruled on the boundaries to obtain between the