Gilles Jullien (c. 1651/1653 – 14 September 1703) was a French Baroque composer and organist. He is credited with bringing the style of French organ music then current in Paris to Chartres. Almost nothing is known about Jullien's life or training. His burial certificate indicates he was 50 or slightly younger when he died, so he must have been born between 1651 and 1653. It is assumed that he became organist of the Chartres Cathedral on 6 December 1667. The date is questionable, but the fact that Jullien was appointed organist of the cathedral while still very young is indisputable. He occupied this position until his death in Chartres in 1703. He was succeeded at the cathedral by his eldest son, Jean-François Jullien.