TEILO (fl. 550), British saint, was born at ‘Eccluis Gunniau (or Guiniau)’ in the neighbourhood of Tenby (Lib. Land. pp. 124, 255). The statement of the life in the ‘Liber Landavensis’ that he was of noble parentage is supported by the genealogies, which make him the son of a man variously called Enoc, Eusych, Cussith, and Eisyllt, and great-grandson of Ceredig ap Cunedda Wledig (Myvyrian Archaiology, 2nd edit. pp. 415, 430; Iolo MSS. p. 124). In the life of Oudoceus in the ‘Liber Landavensis’ the form is Ensic (p. 130). Mr. Phillimore believes (Cymmrodor, xi. 125) the name should be Usyllt, the patron saint of St. Issell's, near Tenby. Teilo's first preceptor was, according to his legend, Dyfrig (cf. the Life of Dyfrig in Lib. Land. p. 80). He next entered the monastic school of Paulinus, where David (d. 601?) [q. v.], his kinsman, was his fellow-pupil. In substantial agreement with the accounts given in the legends of David and Padarn, it is said that the three saints received a divine command to visit Jerusalem, where they were made bishops—a story clearly meant to bring out British independence of Rome. Teilo especially distinguished himself on this journey by his saintly humility and power as a preacher. He received as a gift a bell of miraculous virtue, and returned to take charge of the diocese of Llandaff in succession to Dyfrig. Almost immediately, however, the yellow plague (which is known to have caused the death of Maelgwn Gwynedd about 547) began to rage in Britain, whereupon Teilo, at the bidding of an angel, withdrew to Brittany, spending some time on the way as the guest of King Geraint of Cornwall. When the plague was over it was his wish to return to this country, but, at the instance of King Budic and Bishop Samson [q. v.], he remained in Brittany for seven years and seven months. Returning at last to his bishopric, he became chief over all the churches of ‘dextralis Britannia,’ sending Ismael to fill the place of David at Menevia, and other disciples of his to new dioceses which he created. As his end drew near, three churches, viz. Penally, Llandaff, and Llandeilo Fawr (where he died), contended for the honour of receiving his corpse, but the dispute was settled by the creation of three bodies, a miracle which is the subject of one of the triads (Myv. Arch. 1st ser. p. 44).
This is the Llandaff account of Teilo, meant to bring out his position as second bishop of the see. In Rhygyfarch's ‘Life of St. David,’ written before 1099, Teilo appears, on the other hand, as a disciple of that saint (Cambro-British Saints, pp. 124, 135); and, according to Giraldus Cambrensis (Itinerary, ii. 1, MS. d. vi. 102, of Rolls edit.), he was his immediate successor as bishop of St. David's. There is, however, no reason to suppose he was a diocesan bishop at all. Like others of his age, he founded monasteries (many of them bearing his name), and Llandaff was perhaps the ‘archimonasterium’ (for the term see Lib. Land. pp. 74, 75, 129) or parent house (Cymmrodor, xi. 115–16). Dedications to St. Teilo are to be found throughout South Wales; Rees (Welsh Saints, pp. 245–6) gives a list of eighteen, and a number of other ‘Teilo’ churches, which have disappeared or cannot be identified, are mentioned in the ‘Liber Landavensis.’ That David and Teilo worked together appears likely from the fact that of the eighteen Welsh dedications to Teilo all but three are within the region of David's activity, and outside that district between the Usk and the Tawy in which there are practically no ‘Dewi’ churches.
There are no recognised dedications to Teilo in Cornwall or Devon, though Borlase seeks (Age of the Saints, p. 134) to connect him with Endellion, St. Issey, Philleigh, and other places. The two forms of the saint's name, Eliud and Teilo (old Welsh ‘Teliau’), are both old (see the marginalia of the ‘Book of St. Chad,’ as printed in the 1893 edition of the Lib. Land.) Professor Rhys believes the latter to be a compound of the prefix ‘to’ and the proper name Eliau or Eiliau (Arch. Cambr. 5th ser. xii. 37–8). Teilo's festival was 9 Feb.[Teilo is the subject of a life which appears in the Liber Landavensis (ed. 1893, pp. 97–117), in the portion written about 1150, and also in the Cottonian MS. Vesp. A. xiv. art. 4, which is of about 1200. In the latter manuscript the life is ascribed to ‘Geoffrey, brother of bishop Urban of Llandaff,’ whom Mr. Gwenogvryn Evans seeks (pref. to Lib. Land. p. xxi) to identify with Geoffrey of Monmouth. An abridged version found, according to Hardy (Descriptive Catalogue, i. 132), in Cottonian MS. Tib. E. i. fol. 16, was ascribed to John of Tinmouth [q. v.], was used by Capgrave (Nova Legenda Angliæ, p. 280 b), and taken from him by the Bollandists (Acta SS. Feb. 9, ii. 308); other authorities cited.]