Douglas

Scottish: habitational name from any of the various places called Douglas from their situation on a river named with Gaelic dubh ‘dark’, ‘black’ + glas ‘stream’ (a derivative of glas ‘blue’). There are several localities in Scotland and Ireland so named, but the one from which the surname is derived in most if not all cases is 20 miles south of Glasgow, the original stronghold of the influential Douglas family and their retainers.