Descended from Tomaidh Mòr, a Scottish Gaelic speaking highlander, the MacThomas clan share a common ancestry with clan Mackintosh.
The clan are most associated with the Highlands of Scotland, particularly Perthshire. It is here, just north of Blairgowrie, that the clan settled and located their seat, Finegand.
The current chief of Clan MacThomas is Andrew Patrick MacThomas of Finegand.