Inishtrahull Lighthouse, Ocean navigation lighthouse on Inishtrahull Island, County Donegal, Ireland

Inishtrahull Lighthouse is the 23-metre white tower at the west end of Inishtrahull Island, County Donegal, with a 19-foot lantern above its balcony. It replaced the 1813 east-end light and entered service on 8 October 1958. Its optic was replaced for automation in March 1987, and the station has run on solar power since 20 September 2000.

The first lighthouse structure was built in 1812 to guide British naval vessels and began operating in 1813. This early installation was part of the critical maritime infrastructure of the early 1800s.

The island's name, Inishtrahull, comes from the Irish for "island of the strand of the hole". The station is run by the Commissioners of Irish Lights, and the light is paired with Tory Island as one of the two main landfall lights for ships rounding Ireland's north coast from the Atlantic. The island is a protected area.

The site is closed and can only be reached by helicopter; there is no foot access to the island. Inishtrahull is a protected area, so landings are not a casual option. The station has been unmanned since 30 April 1987 and solar-powered since 20 September 2000.

An advanced fog signal station was installed in 1905 using compressed air to produce consistent directional signals. This technology proved valuable for ships when fog reduced the visibility of the light beam.