Linen () is a textile made from the fibers of the flax plant.

Linen is very strong, absorbent, and dries faster than cotton. Because of these properties, linen is comfortable to wear in hot weather and is valued for use in garments. Linen textiles can be made from flax plant fiber, yarn, as well as woven and knitted. It also has other distinctive characteristics, notably its tendency to wrinkle. It takes significantly longer to harvest than a material like cotton although both are natural fibers. It is also more difficult to weave than cotton.

Linen textiles appear to be some of the oldest in the world; their history goes back many thousands of years. Dyed flax fibers found in a cave in Southeastern Europe (present-day Georgia) suggest the use of woven linen fabrics from wild flax may date back over 30,000 years. Linen was used in ancient civilizations including Mesopotamia and ancient Egypt, and linen is mentioned in the Bible. In the 18th century and beyond, the linen industry was important in the economies of several countries in Europe as well as the American colonies.

Textiles in a linen weave texture, even when made of cotton, hemp, or other non-flax fibers, are also loosely referred to as "linen".