Frigg (/frɪɡ/; Old Norse: [ˈfriɡː]) is a goddess, one of the Æsir, in Germanic mythology. In Norse mythology, the source of most surviving information about her, she is associated with marriage, prophecy, clairvoyance and motherhood, and dwells in the wetland halls of Fensalir. In wider Germanic mythology, she is known in Old High German as Frīja, in Langobardic as Frēa, in Old English as Frīg, in Old Frisian as Frīa, and in Old Saxon as Frī, all ultimately stemming from the Proto-Germanic theonym *Frijjō. Nearly all sources portray her as the wife of the god Odin.

In Old High German and Old Norse sources, she is specifically connected with Fulla, but she is also associated with the goddesses Lofn, Hlín, Gná, and ambiguously with the Earth, otherwise personified as an apparently separate entity Jörð (Old Norse: 'Earth'). The children of Frigg and Odin include the gleaming god Baldr.

The English weekday name Friday (ultimately meaning 'Frigg's Day') bears her name. After Christianization, the mention of Frigg continued to occur in Scandinavian folklore. During modern times, Frigg has appeared in popular culture, has been the subject of art and receives veneration in Germanic Neopaganism.

The theonyms Frigg (Old Norse), Frīja (Old High German), Frīg (Old English), Frīa (Old Frisian), and Frī (Old Saxon) are cognates (linguistic siblings from the same origin). They stem from the Proto-Germanic feminine noun *Frijjō, which emerged as a substantivized form of the adjective *frijaz ('free') via Holtzmann's law. In a clan-based societal system, the meaning 'free' arose from the meaning 'related'. The name is indeed etymologically close to the Sanskrit priyā and the Avestan fryā ('own, dear, beloved'), all ultimately descending from the Proto-Indo-European stem *priH-o-, denoting 'one's own, beloved'. The Proto-Germanic verb *frijōnan ('to love'), as well as the nouns *frijōndz ('friend') and *frijađwō ('friendship, peace'), are also related.

An -a suffix has been sometimes applied by modern editors to denote femininity, resulting in the form Frigga. This spelling also serves the purpose of distancing the goddess from the English word frig, with a primary meaning of masturbate or to the common alternative to the English profanity fuck. Several place names refer to Frigg in what are now Norway and Sweden, although her name is altogether absent in recorded place names in Denmark.

The connection with and possible earlier identification of the goddess Freyja with Frigg in the Proto-Germanic period is a matter of scholarly debate (see Frigg and Freyja common origin hypothesis). Like the name of the group of gods to which Freyja belongs, the Vanir, the name Freyja is not attested outside of Scandinavia. This is in contrast to the name of the goddess Frigg, who is also attested as a goddess among West Germanic peoples. Evidence is lacking for the existence of a common Germanic goddess from which Old Norse Freyja descends, but scholars have commented that this may simply be due to the scarcity of surviving sources.

Regarding the Freyja–Frigg common origin hypothesis, scholar Stephan Grundy writes that "the problem of whether Frigg or Freyja may have been a single goddess originally is a difficult one, made more so by the scantiness of pre-Viking Age references to Germanic goddesses, and the diverse quality of the sources. The best that can be done is to survey the arguments for and against their identity, and to see how well each can be supported."

The English weekday name Friday comes from Old English Frīġedæġ, meaning 'day of Frig'. It is cognate with Old Frisian Frīadei (≈ Fri(g)endei), Middle Dutch Vridach (≈ Vriendach), Middle Low German Vrīdach (≈ Vrīgedach), and Old High German Frîatac. The Old Norse Frjádagr was borrowed from a West Germanic language. All of these terms derive from Late Proto-Germanic *Frijjōdag ('Day of Frijjō'), a calque of Latin Veneris dies ('Day of Venus'; cf. modern Italian venerdì, French vendredi, Spanish viernes).