The kris or keris is a Javanese asymmetrical dagger with a distinctive blade-patterning achieved through alternating laminations of iron and nickelous iron (pamor). The kris is famous for its distinctive wavy blade, although many have straight blades as well, and is one of the weapons commonly used in the pencak silat martial art native to Indonesia. Kris have been produced in many regions of Indonesia for centuries, but nowhere—although the island of Bali comes close—is the kris so embedded in a mutually-connected whole of ritual prescriptions and acts, ceremonies, storied backgrounds, and epic poetry as in Central Java. Within Indonesia the kris is commonly associated with Javanese culture, although other ethnicities in it and surrounding regions are familiar with the weapon as part of their cultures, such as the Balinese, Sundanese, Malay, Madurese, Banjar, Buginese, and Makassar people. The kris itself is considered as a cultural symbol of Indonesia and also neighbouring countries like Brunei, Malaysia, Philippines, Singapore, and Thailand.

A kris can be divided into three parts: blade (bilah or wilah), hilt (hulu), and sheath (warangka). Each part of the kris is considered a piece of art, often carved in meticulous detail and made from various materials: metal, precious or rare types of wood, or gold or ivory. A kris's aesthetic value covers the dhapur (the form and design of the blade, with around 60 variants), the pamor (the pattern of metal alloy decoration on the blade, with around 250 variants), and tangguh referring to the age and origin of a kris. Depending on the quality and historical value of the kris, it can fetch thousands of dollars or more.

Both a weapon and spiritual object, kris are often considered to have an essence or presence, considered to possess magical powers, with some blades possessing good luck and others possessing bad. Kris are used for display, as talismans with magical powers, weapons, a sanctified heirloom (pusaka), auxiliary equipment for court soldiers, an accessory for ceremonial dress, an indicator of social status, a symbol of heroism, etc. Legendary kris that possess supernatural power and extraordinary ability were mentioned in traditional folktales, such as those of Empu Gandring, Taming Sari, and Setan Kober.

In 2005, UNESCO included the Indonesian kris in the Representative List of the Intangible Cultural Heritage of Humanity.

The word kris come from the Old Javanese term which means "dagger". In Javanese, kris is known as keris (ꦏꦼꦫꦶꦱ꧀) in the ngoko register, dhuwung (ꦝꦸꦮꦸꦁ) in the krama register, and wangkingan (ꦮꦁꦏꦶꦁꦔꦤ꧀) in the krama inggil vocabulary. In Malay (subsequently Indonesian and Malaysian), Sundanese, Balinese and Sasak, it is spelled keris (Pegon and Jawi: کريس). Other names include karih in Minangkabau, and sele (ᨔᨙᨒᨙ) in Buginese and Makassarese.

Two notable exceptions are the Philippines and Thailand. In the Philippines, the kris and similar stabbing daggers are known as gunong or gulok, while the much larger slashing sword versions are known as kalis or sundang. The larger kalis sword was introduced from the Sulu Sultanate of the Philippines back to Kalimantan and Sulawesi in Indonesia, where it became known as keris Sulu.

In Thailand it is always spelled kris and pronounced either as kris or krit (กริช) in Thai, while in the Yala dialect, it is spelled kareh. In Cambodia it is spelled as kris (គ្រីស) in Khmer. Other alternative spellings used by Europeans include "cryse", "crise", "criss", "kriss" and "creese". In English, the plural form is often simply "kris" as well.

The term kris was mentioned in several ancient Javanese inscriptions originating from Hindu-Buddhist Mataram Kingdom of Central Java, including Humanding inscription (707 Saka or 875 CE), Jurungan inscription and Haliwangbang inscription (708 Saka or 876 CE), Taji inscription (823 Saka or 901 CE), Poh inscription (827 Saka or 905 CE), and Rukam inscription (829 Saka or 907 CE). Possible renderings of kris also appear on temple bas-reliefs such as of Borobudur (825) and Prambanan temples (850).^{[citation needed]}