Darby is an English surname from the city of Derby, whose Old Norse name combines djur, "deer", and by, settlement, so it means "deer town"; in Ireland it also served as an anglicized form of Diarmaid. Once an Irish boys' name, it has been given to American girls since the 1970s. Darby ranked number 866 in 2000, left the top 1000 in the following years and stands at number 2564 in 2025.