Archangel - appears in Daniel as 'one of the chief princes' - name means 'Who is like unto God'
Principal Feast Sept 29
In the early church Michael was depicted as an angel of majestic majesty who is set over the best part of mankind.
His formal cult began in the East but it was an apparition of Micheal on Monte Gargano (SE Italy) in the late 5th C that spread this cult to the West. The date Sept 29th is that of the dedication of his basilica in Rome.
Falmer states that from early times his cult was strong in the British Isles - often being chosen as a patron of cemeteries. Medieval art often depicted him weighing souls.
Another and now more common representation, dating from somewhat earlier, is as a slayer of dragons.

Kermode gives some history of the Dedication of Churches to St Micahel

The parish of Micheal has contained the residence of the Bishop from at least the early 13th C as the Chronicle of Man records the death of Bishop Simon apud ecclesiam Sancti Michaelis in 1247. (This tradition was broken in the late 1970's with the sale of Bishopscourt). There was also a tradition of Michael as protector - this may have have been a factor in the choice of name as Bishopscourt was certainly built with protection in mind.