In Norse mythology, the Vanir (/ˈvɑːnɪər/; Old Norse:, singular Vanr) are a group of gods associated with fertility, wisdom, and the ability to see the future. The Vanir are one of two groups of gods (the other being the Æsir) and are the namesake of the location Vanaheimr (Old Norse "Home of the Vanir"). After the Æsir–Vanir War, the Vanir became a subgroup of the Æsir. Subsequently, at least some members of the Vanir are at times also referred to as being Æsir.

The Vanir are attested in the Poetic Edda, compiled in the 13th century from earlier traditional sources; the Prose Edda and Heimskringla, both written in the 13th century by Snorri Sturluson; and in the poetry of skalds. The Vanir are attested only in these Old Norse sources.

All sources describe the god Njörðr, and his children Freyr and Freyja as members of the Vanir. A euhemerized prose account in Heimskringla adds that Njörðr's sister—whose name is not provided—and Kvasir were Vanir. In addition, Heimskringla reports a tale involving king Sveigðir's visit to Vanaheimr, where he meets a woman by the name of Vana and the two produce a child named Vanlandi (whose name means "Man from the Land of the Vanir").

While not attested as Vanir, the gods Heimdall and Ullr have been theorized as potential members of the group. In the Prose Edda, a name listed for boars is "Van-child". Scholars have theorized that the Vanir may be connected to small pieces of gold foil found in Scandinavia at some building sites from the Migration Period to the Viking Age and occasionally in graves. They have speculated whether the Vanir originally represented pre-Indo-European deities or Indo-European fertility gods, and have theorized a form of the gods as venerated by the pagan Anglo-Saxons.

Numerous theories have been proposed for the etymology of Vanir. Scholar R. I. Page says that, while there is no shortage of etymologies for the word, it is tempting to link the word with Old Norse vinr ('friend') and Latin Venus ('goddess of physical love'). Vanir is sometimes anglicized to Wanes (singular Wane).

In the Poetic Edda, the Vanir, as a group, are specifically referenced in the poems Völuspá, Vafþrúðnismál, Skírnismál, Þrymskviða, Alvíssmál, and Sigrdrífumál. In Völuspá, a stanza describes the events of the Æsir–Vanir War, noting that during the war the Vanir broke the walls of the stronghold of the Æsir, and that the Vanir were "indomitable, trampling the plain".

In Vafþrúðnismál, Gagnráðr (the god Odin in disguise) engages in a game of wits with the jötunn Vafþrúðnir. Gagnráðr asks Vafþrúðnir where the Van god Njörðr came from, for though he rules over many hofs and hörgrs, Njörðr was not raised among the Æsir. Vafþrúðnir responds that Njörðr was created in Vanaheimr ("home of the Vanir") by "wise powers" and details that during the Æsir–Vanir War, Njörðr was exchanged as a hostage. In addition, when the world ends (Ragnarök), Njörðr "will return to the wise Vanir".

Alvíssmál consists of question and answer exchanges between the dwarf Alvíss and the god Thor. In the poem, Alvíss supplies terms that various groups, including the Vanir, use to refer to various subjects. Alvíss attributes nine terms to the Vanir; one for Earth ("The Ways"), Heaven ("The Weaver of Winds"), clouds ("Kites of the Wind"), calm ("The Hush of the Winds"), the sea ("The Wave"), fire ("Wildfire"), wood ("The Wand"), seed ("growth"), and ale ("The Foaming").