Lactuca serriola, also called prickly lettuce, milk thistle (not to be confused with Silybum marianum, also called milk thistle), compass plant, and scarole, is an annual or biennial plant in the tribe Cichorieae within the family Asteraceae. It has a slightly fetid odor and is commonly considered a weed of orchards, roadsides and field crops. It is the closest wild relative of cultivated lettuce (Lactuca sativa L.).

Lactuca serriola is native to Eurasia and North Africa, and has become naturalized elsewhere.