Kukulkan, also spelled K’uk’ulkan (/kuːkʊlˈkɑːn/; lit. "Plumed Serpent", "Amazing Serpent"), is the serpent deity of Maya mythology. It is closely related to the deity Qʼuqʼumatz of the Kʼicheʼ people and to Quetzalcoatl of Aztec mythology. Prominent temples to Kukulkan are found at archaeological sites in the Yucatán Peninsula, such as Chichen Itza, Uxmal and Mayapan.

The depiction of the Feathered Serpent is present in other cultures of Mesoamerica. Although heavily Mexicanised, Kukulkan has its origins among the Maya of the Classic Period. Little is known of the mythology of this Pre-Columbian era deity.

In the Yucatec Maya language, the name is spelt Kʼukʼulkan (/kʼuː kʼuːlˈkän/) and in Tzotzil it is Kʼukʼul-chon (/kʼuːˈkʼuːl tʃʰon/). The Yucatec form of the name is formed from the word kuk "feather" with the adjectival suffix -ul, giving kukul "feathered", combined with kan "snake" (Tzotzil chon), giving a literal meaning of "feathered snake". In the Chol-Ch'orti'-Tzeltal family of languages, Kukulcan is Kukulchon. In Ch'orti', Kukulchon is kuk k'ur chon.

Kukulkan has its origins among the Maya of the Classic Period, when it was known as Waxaklahun Ubah Kan (/waʃaklaˈχuːn uːˈɓaχ kän/), the War Serpent. It has been identified also as the Postclassic version of the Vision Serpent of Classic Maya art.

The cult of Kukulkan/Quetzalcoatl was the first Mesoamerican religion to transcend the old Classic Period linguistic and ethnic divisions. This cult facilitated communication and peaceful trade among peoples of many different social and ethnic backgrounds. Although the cult was originally centred on the ancient city of Chichen Itza in the modern Mexican state of Yucatán, it spread as far as the Guatemalan Highlands and northern Belize.

In Yucatán, references to the deity Kukulkan are confused by references to a historical individual who bore the name of the god. Because of this, the distinction between the two has become blurred. This individual appears to have been a ruler or priest at Chichen Itza who first appeared around the 10th century. Although Kukulkan was mentioned as a historical person by Maya writers of the 16th century, the earlier 9th-century texts at Chichen Itza never identified him as human and artistic representations depicted him as a Vision Serpent entwined around the figures of nobles. At Chichen Itza, Kukulkan is also depicted presiding over sacrifice scenes.

Kukulkan was a deity closely associated with the Itza state in the northern Yucatán Peninsula, where the religion formed the core of the Territorial religion. Although the worship of Kukulkan had its origins in earlier Maya traditions, the Itza worship of Kukulkan was heavily influenced by the Quetzalcoatl religion of central Mexico. This influence probably arrived via Putún Maya merchants from the Gulf Coast of Mexico. These Chontal merchants probably actively promoted the feathered serpent worshipers throughout Mesoamerica. Kukulkan headed a pantheon of deities of mixed Maya and non-Maya provenance, used to promote the Itza political and commercial agenda. It also eased the passage of Itza merchants into central Mexico and other non-Maya areas, promoting the Itza economy.

At Chichen Itza, Kukulkan ceased to be the Vision Serpent that served as a messenger between the king and the gods and came instead to symbolise the divinity of the territory.