Clarksville (also known as Clarksville Junction) is a small township located three kilometres southwest of Milton in the Otago region of the South Island of New Zealand. State Highways 1 and 8 meet in Clarksville. The town was also once the location of a railway junction, where the Roxburgh Branch left the Main South Line. Construction of this branch line began in the 1870s and Clarksville acted as the junction until 1907, when an extension of the branch was built alongside the Main South Line into Milton to improve operations.