L'Ost-Pic, Stone lighthouse in Plouézec, France.

L'Ost-Pic is a 15-meter tall stone lighthouse located on the coast near Plouézec in Brittany. The structure stands roughly 22 meters above sea level and features traditional stonework typical of French coastal beacons.

Construction was approved by ministerial decision on 3 November 1892, and the Stourm company began work in May 1893. The lighthouse was built in 1893–1894 and lit on 15 August 1894; it was then the first in France to have an officially designated pair of keepers. It was automated in 1911. In 1944 German troops destroyed the upper part, and it was rebuilt and relit on 19 March 1948.

The name Lost Pic comes from Breton lost pic, "magpie's tail" or "pointed tail", describing the rock as the last in the chain of the Mez-de-Goëlo reef. The spelling L'Ost-Pic, carved on the tower's north-east face, has no meaning in Breton or French and is likely a writing error.

The lighthouse can be viewed from exterior vantage points that offer views of the surrounding rocky coastline and Atlantic waters. Sturdy footwear is advisable due to the uneven terrain and exposed rocks in the area.

The name on the north-east face reads "L'Ost-Pic", but the Breton name Lost Pik means "magpie's tail" or "pointed tail", describing the rock as the last in a line trailing from the great Mez de Goëlo reef. The form L'Ost-Pic has no meaning in Breton or French and is likely a misspelling.