Loch Lochy (Scottish Gaelic, Loch Lochaidh) is a large freshwater loch in Lochaber, Highland, Scotland.

Situated 16 kilometers southwest of Loch Ness along the Great Glen, the loch is over 15 kilometers long with an average width of about 1 kilometer. The River Lochy flows from its southwestern end while the Caledonian Canal links its northwestern extent to Loch Oich.

It is here were the Battle of the Shirts took place involving Clan Donald and Clan Fraser.

Lizzie, a three-humped, plesiosaur-like creature akin to the Loch Ness monster, is reputed to live in the waters of Lochy