Saffron (/ˈsæfrən, -rɒn/)[1] is a spice derived from the flower of Crocus sativus, commonly known as the "saffron crocus". The vivid crimson stigma and styles, called threads, are collected and dried for use mainly as a seasoning and colouring agent in food. The saffron crocus was slowly propagated throughout much of Eurasia and was later brought to parts of North Africa, North America, and Oceania.

Saffron's taste and iodoform-like or hay-like fragrance result from the phytochemicals picrocrocin and safranal. It also contains a carotenoid pigment, crocin, which imparts a rich golden-yellow hue to dishes and textiles. Its recorded history is attested in a 7th-century BC Assyrian botanical treatise, and it has been traded and used for thousands of years. As of 2018, Iran produced some 88% of the world total for saffron. At US$5,000 per kg or higher, saffron has long been the world's costliest spice by weight.

A degree of uncertainty surrounds the origin of the English word "saffron". It might stem from the 12th-century Old French term safran, which comes from the Latin word safranum, from the Persian (زعفران, za'farān), from the Persian word zarparān (زرپران) meaning "gold strung" (implying either the golden stamens of the flower or the golden colour it creates when used as flavour).

The domesticated saffron crocus, Crocus sativus, is an autumn-flowering perennial plant unknown in the wild. It probably descends from the eastern Mediterranean autumn-flowering Crocus cartwrightianus which is also known as "wild saffron" and is native to mainland Greece, Euboea, Crete, Skyros and some islands of the Cyclades. The similar species C. thomasii and C. pallasii were considered as other possible ancestors.  As a genetically monomorphic clone incapable of seed production, it was slowly propagated by humans throughout much of Eurasia.