Marc de Champagne is one of 30 appellations for French eaux-de-Vie, specifically covering those spirits produced within the Champagne wine region.
Marc is grape pomace: the residual skins and seeds left behind after pressing. Under the Eau-de-Vie de Marc de Champagne appellation only this dry residue may be fermented, absent of grape juice. The grape varieties used are, for obvious reasons, those which are key in Champagne: Pinot Noir, Pinot Meunier and Chardonnay.
Because only dry skins and pips are employed to make Marc de Champagne, the resulting spirit has less of a fruity character than those distilled from complete must and is reliant on mouthfeel rather than flavors. Italian grappa is made in a very similar way to eaux de Vie de Marc.
Marc de Champagne (the spirit) is not to be confused with the identically pronounced Grand Marque de Champagne ('great brand of champagne'), which is used when referring to the names of the most-prestigious champagne houses.
