Sisal (, Spanish: [siˈsal]) (Agave sisalana) is a species of flowering plant native to southern Mexico, but widely cultivated and naturalized in many other countries. It yields a stiff fibre used in making rope and various other products. The term sisal may refer either to the plant's common name or the fibre, depending on the context. The sisal fibre is traditionally used for rope and twine, and has many other uses, including paper, cloth, footwear, hats, bags, carpets, geotextiles, and dartboards. It is also used as fibre reinforcements for composite fibreglass, rubber, and concrete products. It can also be fermented and distilled to make mezcal.

Sisal has an uncertain native origin, but is thought to have originated in Chiapas, Mexico. Sisal plants have a lifespan of 7–10 years, producing 200–250 usable leaves containing fibers used in various applications. Sisal is a tropical and subtropical plant, thriving in temperatures above 25°C and sunshine.

Historically, sisal was used by the Aztecs and Mayans for fabric and paper. It spread to other parts of the world in the 19th century, with Brazil becoming the major producer. Sisal is propagated using bulbils or suckers and can be improved genetically through tissue culture. Fibers are extracted through decortication and then dried, brushed, and baled for export.

Sisal farming initially led to environmental degradation, but it is now considered less damaging than other farming types. It is an invasive species in Hawaii and Florida.

Global sisal production in 2020 was 210,000 tonnes, with Brazil being the largest producer, followed by Tanzania, Kenya, Madagascar, China, and Mexico.