- An Irish surname, variant of the Scottish Colquhoun.
- A city in Georgia that is the county seat of Gordon County.
- A village in Richland County, Illinois.
- A city in Kentucky that is the county seat of McLean County.
- A city in Henry County, Missouri.
- The former name of Clemson, South Carolina, until it was renamed in 1943.
- A town in McMinn County, Tennessee.
- An unincorporated community in Barbour County, West Virginia.
- (education) Calhoun College.