Lancieux (French pronunciation: [lɑ̃sjø] ⓘ; Breton: Lanseeg; Gallo: Lansioec) is a commune in the Côtes-d'Armor department of Brittany in northwestern France.

Lancieux derives its name from the Breton lann ("hermitage") and Seoc, Cieux, or Sieu, a monk who came from British Cornwall at the end of the 6th century AD; therefore it can be translated as "the hermitage of Seoc".

The British-Canadian poet and writer Robert W. Service, known as the "Bard of the Yukon", used to spend summers in Lancieux from 1913 until his death in 1958.

On many occasions, he made monetary gifts to the town, including for the school and the war memorial.

[4] The town of Lancieux has paid homage to the memory of Robert W. Service.