Kilmodan is a civil parish situated on the Cowal Peninsula, in Argyll and Bute, west of Scotland.
It is bounded by Loch Riddan, and by the parishes of Kilfinan, Strachur, Dunoon, and Inverchaolain.
It consists chiefly of a glen, flanked by high hills, and extending southward; and is about 12 miles (19 km) long.
The River Ruel traverses the upper part of the glen, and falls into the head of Loch Riddan.
The most well-known native of the parish is Colin Maclaurin, professor of mathematics at the University of Edinburgh.