Papal Nuncio Tacitus (4 March 501-) was Papal nuncio to Britannia from 27 February 530, succeeding Papal Nuncio Ambrosinus. He was sent by Pope Felix IV to serve as head of the Roman Catholic Church in Gaul, Britain, and Ireland, and, by the time of his appointment, Christianity was spreading quickly and pushing into the valleys of Powys and Gwynedd as paganism continued to decline across all of Western Europe.