Saint-Julien-d'Arpaon (; ) is a former commune in the Lozère department in southern France. On 1 January 2016, it was merged into the new commune of Cans-et-Cévennes. Its population was 94 in 2022.
Saint-Julien-d'Arpaon stands at a crossing of the river Mimente on the Robert Louis Stevenson Trail (GR 70), a popular long-distance path following approximately the route travelled by Robert Louis Stevenson in 1878 and described in his book Travels with a Donkey in the Cévennes. Stevenson mentions the village and its ruined chateau in passing, though not by name: