Colquhoun (/kəˈhuːn/ kə-HOON) is a surname of Scottish origin.^[1] It is a habitational name from the barony of Colquhoun in Dunbartonshire.^[1] The Scottish Clan Colquhoun originated there. The name is possibly derived from the Gaelic elements còil ("nook"), cùil ("corner"), or coill(e) ("wood") + cumhann ("narrow"), or comh-thonn ("wave crash").^[2] The "l" is typically silent per developments in the Scots language.

Phonetically, MacOlquhoun is similar to MacElhone/MacIlhone and therefore Colquhoun may sometimes derive from the Gaelic name Mac Giolla Còmhghan.^[3] Còmhghan is derived from comh ("together") and gan-, gen- ("born").^[4]

Calhoun, Colhoun, Calhoon, Colhoon, Cohoon, Hoon, Cahoun, and Cahoon are variants of the surname Colquhoun. They are generally found as simplifications and respellings, though all of them can occur from unrelated sources. In particular, Calhoun is from the Irish variant of Colquhoun.

• Cahoon, a variant name
• Cohoon, a variant name
• Colhoun (disambiguation), a variant name
• Clan Colquhoun, a Scottish clan bearing the name
• Colquhoun Peak, a mountain in Washington state