Tirefour Castle, (or Tirefour Broch, also spelled Tirfuir and Tirrefour) is an Iron Age broch located 4 kilometres north of Achnacroish on the island of Lismore, Scotland.

Tirefour Castle (grid reference NM86754290) is situated on a rocky height on the east coast of the island of Lismore.

[1][3] It was inhabited during the Roman era as shown by the discovery of an enamel brooch in the foundation layer.

On the northwestern and eastern sides, at a height of 2.5 metres above the original ground level, intramural galleries can be seen.

[5][8] In 2010, beneath the earth on the north side, a 1 metre wide opening was found, which probably gave access to an intramural room or staircase.

[2] Surrounding the broch can be seen traces of two walls, which offered additional protection to the northeast and southwest sides.