Milk-cap (also milk cap, milkcap, or milky) is a common name that refers to mushroom-forming fungi of the genera Lactarius, Lactifluus, and Multifurca, all in the family Russulaceae. The common and eponymous feature of their fruitbodies is the latex ("milk") they exude when cut or bruised. Mushrooms with typical milk-cap characteristics are said to have a lactarioid habit. Some of them are edible.

Historically, these species were all united in the genus Lactarius, but molecular phylogenetic analysis has shown that they belong in fact to three distinct clades:

• Lactarius holds most of the milk-caps known from the Northern hemisphere.
• Lactifluus contains mainly tropical species, but also some well known northern milk-caps.
• Multifurca contains only one species exuding milk, M. furcata from North and Central America.