Rosguill (Irish language and official name: Ros Goill) is a peninsula situated in north-north-west County Donegal, Ireland. Lying between the peninsulae of Fanad to the east and Horn Head to the west, Rosguill is a dichotomy of heathland and ocean. With the great Sheephaven Bay with its mellow waters and pure-white strands on the one hand, and the treacherous sand banks of Mulroy Bay on the other. Between, a mixture of bog, hill and pastureland, the ancient walls, remnants of cattle enclosures, and the various evidences of fortification are proof of the area's use since antiquity. The Parish of Rosguill is an alternative name for the Parish of Mevagh, which covers the peninsula and an equally sized hinterland.
There are nearly 800 people living in Rosguill ED and 33% of residents are native Irish speakers.
 History and folklore
The area is heavy with legend, the name itself is supposed to have originated, when Fionn mac Cumhaill finally obtained justice by killing Goll mac Morna, the slayer of his father. This act is traditionally said to have taken place at a rock called Carraic Ghoill (English: Carrickguill) lying off the townland of Dumhaigh (English: Dooey). The entire area became known as the "Headland of Goll" or Ros Goill.
The highest point on the peninsula is Gainne Mhór and its sister peak Gainne Bheag. The name derives from Gráinne, betrothed of Fionn mac Cumhaill and lover of Diarmuid Ua Duibhne. While fleeing Fionn's Fianna warriors en route to Scotland, legend has it that they rested on the hill. Considerable damage to the south western face of Gainne has been the result of unrestrained excavation in recent years. It was also used as a dump for a period. Nach mór a' náire (What a shame).
In the late 4th century the son of Niall Noigíallach and the eponym of County Donegal (Tír Conaill), Conall Gulban, defeated the warriors of Ulaid, at Ballyshannon and Barnesmore. Conall's army chased the fleeing Ulstermen through Goll (Rosguill), Crích Chloinne Rosa, Crích Ua nDuach, Caim-Fhersaid Mhór, to the shores of Lough Foyle. Conalll Gulban and his brother Eógan, became the ancestors of the Kings of Tír Conaill (Tyrconnell) and Tír Eógain (Tyrone) respectively.
 Colm Cille
In common with many other areas of Donegal and Ulster, Rosguill has its share of legends relating to St. Colm Cille. Colm Cille was a nobleman born at Gartan, a great-grandson of Conall Gulban, he took holy orders and began proselytising throughout Ireland. Prior to his exile in Dál Riata and the Kingdom of the Picts, Colm Cille founded monasteries at Derry and Kells, and is accredited with the founding of many more smaller establishments. Of these the Old church at Mevagh, in Clontallagh townland is said to one. Colm Cille also is said to have erected the High cross in the churchyard, on which allegedly he left the track of his fingers in the stone. Furthermore he spread curses and blessings on various townlands in the parish in equal measure to the hospitality he received: Dundoan Upper was cursed to always have a fool amongst its community, after they mocked him, whereas he prophesied that no-one from Dooey or Island Roy would ever drown. His supposed footprints are to be found on a rock in Downings.
"MEVAGH, or MOYVAGH, a parish, in the barony of KILMACRENAN, county of DONEGAL, and province of ULSTER, 14 miles (N. by W.) from Letterkenny; containing 4794 inhabitants. This parish comprises, according to the Ordnance survey, 21,0261⁄2 statute acres, of which 3821⁄2 are water, and 18,393 are applotted under the tithe act; the greater part of the land is poor, a small portion only being considered very good. There is a great quantity of bog and waste land; the latter consists of large tracts of sand thrown up by the sea. Lead has been discovered but is not at present worked. It is situated on Mulroy bay, and within its limits is the peninsula of Rossgul, bounded on the west by Sheephaven, on the north by the ocean, and on the east by the arm of the sea called Mulroy: in the centre this peninsula rises into great elevations, and near the shore presents a stunted verdure. The harbour of Mulroy, by the line of coast, is 5 miles (8.0 km) to the west of Lough Swilly; it has water sufficient for the largest ships, and is well sheltered, but part of the channel is narrow and difficult. On the 14th of every month a fair is held in Glen; and petty sessions are held on alternate Saturdays. The living is a rectory and vicarage, in the diocese of Raphoe, and in the patronage of the Bishop: the tithes amount to £375; the glebe, about two miles (3 km) from the church, comprises 1841⁄4 statute acres, valued at £30 per ann., of which 251⁄4 acres are arable, and the remainder rocky pasture and mountain, with the exception of 21⁄4 consisting of streets and commons. The church is in good repair; it was built about 160 years since. The R. C. parish is co-extensive with that of the Established Church: the chapel is a good slated building. About 230 children are educated in four public schools, of which the parochial school is aided by an annual donation from Colonel Robertson's Fund; and in three private schools are about 130 children: there are also three Sunday schools. At the time of Pynnar's survey, a strong bawn of lime and stone, sixty feet square, with flankers, stood here; and there were 23 British families, capable of mustering forty-two fighting men."
from 'A Topographical Dictionary Of Ireland', by Samuel Lewis, 1837
There is a wealth of activities available locally: Angling, Hiking, Golf and Watersports. One of the most eastern of all Gaeltachtaí, the area has a vibrant cultural tradition, with many artists and musicians residing in the area
Rosguill has been victim to some extent to, the short sighted planning of the 1990s, and to the almost absence of applied legislation previously and, like a great deal of the west coast of the country, has suffered from unchecked ribbon development. However, one can easily escape this, except in the main settlements, to find an Ireland of centuries past.
Downings Harbour in Sheephaven Bay is fast becoming a world class big game fishing destination. Each autumn, sport fishing charter boats use Downings as the launching point for giant bluefin tuna fishing charters. See  for additional information.
The western side of the Rosguill peninsula and its townlands are known colloquially as "The Bottom" and the eastern side is known as "The Far side". The townlands on the mainland are known as "The Upper Part".
The peninsula of Rosguill consists of nineteen Townlands:
There are a further thirty one townlands in the parish of Rosguill (Mevagh):
 Notable natives
- Most Reverend Philip Boyce - present Bishop of Raphoe
- The Most Reverend Dr. Daniel McGettigan - former Lord Archbishop of Armagh
- Placenames (Ceantair Ghaeltachta) Order 2004.
- Statistical Survey of the County of Donegal with Observations on the Means of Improvement, Drawn up in the year 1801, For the consideration and under the direction of The Dublin Society, by James McParlan M.D.
- A TOPOGRAPHICAL DICTIONARY OF IRELAND, COMPRISING THE SEVERAL COUNTIES, CITIES, BOROUGHS, CORPORATE, MARKET, AND POST TOWNS. PARISHES, AND VILLAGES, WITH HISTORICAL AND STATISTICAL DESCRIPTIONS; EMBELLISHED WITH ENGRAVINGS OF THE ARMS OF THE CITIES, BISHOPRICKS, CORPORATE TOWNS, AND BOROUGHS; OF THE SEALS OF THE SEVERAL MUNICIPAL CORPORATIONS: APPENDIX, DESCRIBING THE ELECTORAL BOUNDARIES OF THE SEVERAL BOROUGHS, AS DEFINED BY THE ACT OF THE 2d & 3d OF WILLIAM IV. BY SAMUEL LEWIS. IN TWO VOLUMES. VOL. I. LONDON: PUBLISHED BY S. LEWIS & Co. 87, ALDERSGATE STREET. MDCCCXXXVII.
Lucas, Leslie W. More about Mevagh 2nd ed. ( Appletree Press,1982)