Duncan is a Scottish name meaning dark warrior, the equivalent in Gaelic being Donnacha. It may be used as a surname or boy's first name. It is the name of several people, including two Scottish kings, several places in the United States, and six ships of the Royal Navy.

Kings

• Duncan I of Scotland (d. 1040) - appears as a character in the play Macbeth
• Duncan II of Scotland (1060 - 1094)

Places

Duncan is the name of a number of places in the United States and Canada:

• Duncan , Alabama
• Duncan, Arizona
• Duncan , Arkansas
• Duncan, British Columbia
• Duncan , Colorado
• Duncan , Illinois
• Duncan , Indiana
• Duncan , Iowa
• Duncan , Mercer County, Kentucky
• Duncan , Mercer County, Kentucky
• Duncan, Mississippi
• Duncan , Webster County, Missouri
• Duncan , Wright County, Missouri
• Duncan, Nebraska
• Duncan , North Carolina
• Duncan, Oklahoma
• Duncan , Oregon
• Duncan , Pennsylvania
• Duncan, South Carolina
• Duncan , Tennessee
• Duncan , Virginia
• Duncan , Washington
• Duncan , West Virginia

In addition, there is Duncanville, Texas.

Others

• HMS Duncan, named after a British admiral, Adam Duncan. May also refer to a Jubilee class loco, and a character in the Thomas the Tank Engine series.
• USS Duncan, the name of several US warships.
• Duncan is the name of He-man's Man-at-arms from the Masters of the Universe toyline, comics and cartoon.