Saint-Julien-le-Pauvre, in full Église Saint-Julien-le-Pauvre (French for Church of Saint Julian the Poor), is a Melkite Greek Catholic parish church in Paris, France, and one of the city's oldest religious buildings. Built in Gothic style during the 13th century, it is situated in the 5th arrondissement, on the Left Bank of the Seine River, about 500 meters away from the Musée de Cluny and in the proximity of the Maubert-Mutualité Paris Métro station. It shares a city block with the Square René Viviani.
Originally a Roman Catholic place of worship, Saint-Julien-le-Pauvre was built in stages from the 12th to the 19th centuries, and granted to the Eastern Catholic Melkite community in 1889. Its original design was modified several times, and the resulting church is significantly smaller in size than originally planned.
Saint-Julien-le-Pauvre was designed in the conservative tradition prevalent during the rule of King Louis the Younger. The only one of the city's twelfth-century parish churches to have endured, it was never completed in its original design: the choir area was intended to be three stories high, and the clerestory is an incomplete triforium; the nave was supposed to be covered by sexpartite vaults, which were replaced by a wooden roof and, after the 17th century, by a new system of vaults; and, of a tower meant to stand on the church's southern side, only the staircase was begun. The eastern apses use material from an older building.
The building has piers replicating those found in Notre Dame, and the chapiters are carved with images of leaves and harpies. The choir area is presently covered by an iconostasis. North of the church, in the Square René Viviani, exists the oldest tree in Paris. It is a locust tree planted in 1602 by Jean Robin, gardener-in-chief during the reign of kings Henry III, Henry IV, and Louis XIII. Also known as the "Lucky Tree of Paris", it is thought to bring years of good luck to those who gently touch the tree's bark.