New Castle Lachlan

New Castle Lachlan, is an 18th-century baronial mansion or country house located at Strathlachlan, on the Cowal Peninsula, in Argyll and Bute, west of Scotland. It was built in 1790 by Donald Maclachlan, 19th laird, to replace the 15th century Old Castle Lachlan, which stands nearby on the shores of Loch Fyne. The building is protected as a category C listed building.

The building was remodelled around 1910 by the architect George Mackie Watson.