Castle Stalker, Medieval tower house in Argyll and Bute, Scotland.

Castle Stalker is a four-storey tower house on a tidal islet in Loch Laich. Its rectangular main block of grey-brown rough stone has a taller round tower at the left corner capped by a dark conical roof, crow-stepped gables and small chimney stacks. Two rows of small windows face the water, and a doorway is reached by a stone slipway sloping to the water.

The Stewarts built the present tower in the 1440s after gaining control of the Lordship of Lorn from Clan MacDougall in 1388. Ownership later passed several times between different Scottish families before the structure underwent restoration in the 20th century.

The name derives from the Gaelic word "Stalcaire", pointing to the hunting activity once practiced in this area. Today the tower stands as a landmark of the western Scottish coast, often photographed by travelers passing along the loch.

Visits are possible during summer through guided tours that should be booked well in advance, as the islet is accessible only at certain tidal conditions. A view from the mainland also offers a good look at the tower, which stands out against the backdrop of the surrounding mountains.

King James VI of Scotland, a relative of the Stewarts, visited the castle, and a drunken bet around 1620 led to it passing to Clan Campbell. The island was recorded by the National Records of Scotland as having no usual residents at the 2001 and 2011 censuses. The castle appears as "The Castle Aaaaarrrrrrggghhh" in Monty Python and the Holy Grail.