Douglas is a Scottish name derived from "Dubhglas", meaning "dark stream". It has a long historical background, associated with notable figures like William Douglas who fought at Battle of Bannockburn, and Archibald Douglas, 5th Earl of Angus. In literature, it's known for appearing in Sir Walter Scott's novel "The Bride of Lammermoor". Today, Douglas remains popular as both a first name and surname, often associated with strength and Scottish heritage.