The progenitor of the Clan MacThomas was Thomas, who was a Scottish Gaelic speaking Highlander. He was known as Tomaidh Mòr and it is from him that the clan takes its name. He was a grandson of William Mackintosh, 7th chief of Clan Mackintosh and 8th chief of the Chattan Confederation. Thomas lived in fifteenth century when the Clan Chattan had become so large that it was unmanageable, so Thomas took his clan from Badenoch, across the Grampian Mountains to Glen Shee where they re-settled. Here they flourished and became known as McComie, McColm and McComas which are phonetic forms of the Gaelic. The Clan MacThomas was described in a roll of the clans, in the Acts of Parliament of 1587 and 1595, and they were known to the government in Edinburgh as Macthomas.