Marmite ( MAR-myte) is a British savoury food spread based on yeast extract, invented by the German scientist Justus von Liebig. It is made from by-products of beer brewing (lees) and is produced by the British company Unilever. Marmite is a vegan source of B vitamins, including supplemental vitamin B₁₂. A traditional method of use is to spread it very thinly on buttered toast.

Marmite is a sticky, dark brown paste with a distinctive, salty, powerful flavour and heady aroma. This distinctive taste is represented in the marketing slogan: "Love it or hate it." Such is its prominence in British popular culture that Marmite is often used as a metaphor for something that is an acquired taste or polarises opinion. Marmite is commonly used as a flavouring, as it is particularly rich in umami due to its very high levels of glutamate (1960 mg/100 g).

The image on the jar shows a marmite (French: [maʁmit]), a French term for a large, covered earthenware or metal cooking pot. Marmite was originally supplied in earthenware pots but since the 1920s has been sold in glass jars. Marmite's distinctive bulbous jars are supplied to Unilever by the German glass manufacturer Gerresheimer.

Similar products include the Australian Vegemite (whose name is derived from that of Marmite), the Swiss Cenovis, the Brazilian Cenovit, the long-extinct Argentinian Condibé, and the German Vitam-R. Marmite in New Zealand has been manufactured since 1919 under licence, but with a different recipe; it is the only one sold as Marmite in Australasia and the Pacific Islands, whereas elsewhere the British version predominates.