Malbec (pronounced [mal.bɛk]) is a purple grape variety used in making red wine. The grapes tend to have an inky dark color and robust tannins, and are known as one of the six grapes allowed in the blend of red Bordeaux wine. In France, plantations of Malbec are now found primarily in Cahors in South West France, though the grape is grown worldwide. It is increasingly celebrated as an Argentine varietal.

The grape became less popular in Bordeaux after 1956 when frost killed off 75% of the crop. Despite Cahors being hit by the same frost, which devastated the vineyards, Malbec was replanted and continued to be popular in that area. Winemakers in the region frequently mixed Malbec with Merlot and Tannat to make dark, full-bodied wines, but have ventured into 100% Malbec varietal wines more recently.

A popular but unconfirmed theory claims that Malbec is named after a Hungarian peasant who first spread the grape variety throughout France. French ampelographer and viticulturalist Pierre Galet notes, however, that most evidence suggests that Côt was the variety's original name and that it probably originated in northern Burgundy. Due to similarities in synonyms, Malbec is often confused with other varieties of grape. Malbec argenté is not Malbec, but rather a variety of the southwestern French grape Abouriou. In Cahors, the Malbec grape is referred to as Auxerrois or Côt Noir; this is sometimes confused with Auxerrois blanc, which is an entirely different variety.

The Malbec grape is a thick-skinned grape and needs more sun and heat than either Cabernet Sauvignon or Merlot to mature. It ripens mid-season and can bring very deep color, ample tannin, and a particular plum-like flavor component which adds complexity to claret blends. Sometimes, especially in its traditional growing regions, it is not trellised but is instead cultivated as bush vines (the goblet system). In such cases, it is sometimes kept to a relatively low yield of about 6 tons per hectare. Wines produced using this growing method are rich, dark, and juicy.

As a varietal, Malbec creates a rather inky red (or violet), intense wine, so it is also commonly used in blends, such as with Merlot and Cabernet Sauvignon to create the red French Bordeaux claret blend. The grape is blended with Cabernet Franc and Gamay in some regions such as the Loire Valley. Other wine regions use the grape to produce Bordeaux-style blends. The varietal is sensitive to frost and has a propensity for shattering or coulure.