Colby \c(o)-lby, col-by\ as a boy's name is pronounced KOHL-bee. It is of Old Norse origin, and the meaning of Colby is "swarthy person's settlement". From the personal name Koli (from "kol" meaning "charcoal"). There was a 1980s television series "The Colbys". See also Kolby.
For more information, see also the related name Colton.