Breachacha Castle is either of two structures on the shore of Loch Breachacha, on the Inner Hebridean island of Coll, Scotland. The earlier is a 15th-century tower house that was a stronghold of the Macleans of Coll, the island having been granted to John Maclean in 1431. This castle was superseded by a new dwelling in 1750 but continued to be occupied for a time. It fell into a ruinous state only in the mid-19th century.