Scottish Border Reiver Clan
With the Armstrongs, Elliots, and Nixons. Some sources cite the surname as a sept of the Armstrong clan, but the Scottish Parliament in 1587 identified the Croziers as a middle march clan.
An armigerous clan is a clan without a chief, and a sept is a clan which follows a chief. So an armigerous clan like Clan Armstrong, since it does not have a chief, does not have septs. Clan Crozier, not having a chief by the Lord Lyon King of Arms, is an armigerous clan allied with the far more populous Clan Armstrong.