The main group of this name belonged to the Clan Chattan Confederation and their name was usually anglicised to MacThomas. This branch descend from Tomaidh Mor or Great Thomas, a descendant of the Clan Chattan MacKintoshes who lived in the 15th century and who led his followers out of Badenoch to the other side of the Grampians to Glenshee. A charter in 1571 confirmed John McComy-Muir the lands of Finegand Glenshee, where the 4th chief Robert McComie was murdered. The MacThomases were named as one of the "broken" clans in the late 16th century, but their Gathering ground is still marked today near Glenshee. During the Civil wars the MacThomas chief apparently acted as a government agent, however Iain Mor, 7th chief joined Montrose at Dundee in 1644. The MacThomases were often involved in feuds amongst their neighbours, especially the Farquharsons. There was another branch called Thomason whose ancestor was the son of a MacFarlane chief called Thomas, who were septs of the MacFarlanes. In 1964 Sir Roy Thomson, proprietor of the newspapers throughout the world was created 1st Lord Thomson of Fleet, but the Laird of Clan MacThomas is now Andrew MacThomas of Finegand.
