The Gulf languages are a proposed family of native North American languages composed of the Muskogean languages, along with four language isolates: Natchez, Tunica, Atakapa, and (possibly) Chitimacha.

Gulf was proposed as a language family by Mary Haas (Haas 1951,^[1] 1952^[2]), but the family has not been rigorously established by the comparative method. Historical linguists such as Lyle Campbell (Campbell and Mithun 1979,^[3] Campbell 1997^[4]) list the relationship as unproven, though a number of Muskogean scholars believe that Muskogean is at least related to Natchez (Campbell 1997:305).

However, the Gulf hypothesis is considered by a number of specialists on Muskogean languages, including Mary Haas and Pamela Munro. Munro (1995) has regarded the hypothesis of a Gulf family of languages as promising; Haas thought the closest language to Muskogean would be Natchez, followed by Tunica, Atakapa, and, rather dubiously, Chitimacha.^[5] A difficulty in evaluating the hypothesis is the lack of available data. Most of the data on Chitimacha and Natchez is still unpublished and held in archives.

Additionally, Haas (1958) proposed that the Gulf languages are related to the Algonquian languages.^[6]

Lexical comparisons by Kimball (1994) showing areal similarities among the "Gulf" languages:^{[7]: 35–38}

Below are pronouns comparisons by Geoffrey Kimball (1994) showing areal similarities among the "Gulf" languages.^[7]: 39 Note that Tunica distinguishes masculine and feminine pronominal forms.

• Calusa–Tunica languages