Slieve Gallion (Irish: Sliabh gCallann)[1][2] is a mountain in County Londonderry, Northern Ireland.

[2] Its prominent northeastern summit has a transmitter station with a small road leading to it, and stands at a height of 496 metres (1,627 ft).

To the west, the landscape consists of blanket bog and coniferous forest;[3] most of the trees in the Slieve Gallion area are Sitka spruce.

[8] The earliest reference to Slieve Gallion is from the 7th century, in the Book of Armagh, where it is called Collunt Patricii, likely meaning "the height of Saint Patrick".

[8] There was formerly a challenge walk/run from the village of Moneymore to the summit of Slieve Gallon, which took participants through idyllic countryside such as Cairndaisy glen and the Postmans Way.

This site is considered a good starting point to go cross-country as there is little in the way of airspace restrictions in a downwind direction from its predominate flyable faces.