Hittite (Hittite cuneiform: 𒌷𒉌𒅆𒇷, romanized: nešili, lit. 'in the language of Neša', or nešumnili lit. 'in the language of the people of Neša'), also known as Nesite (Nešite/Neshite, Nessite), is an extinct Indo-European language that was spoken by the Hittites, a people of Bronze Age Anatolia who created an empire centered on Hattusa, as well as parts of the northern Levant and Upper Mesopotamia. The language, now long extinct, is attested in cuneiform, in records dating from the 17th (Anitta text) to the 13th centuries BC, with isolated Hittite loanwords and numerous personal names appearing in an Old Assyrian context from as early as the 20th century BC, making it the earliest attested use of the Indo-European languages.

By the Late Bronze Age, Hittite had started losing ground to its close relative Luwian. It appears that Luwian was the most widely spoken language in the Hittite capital of Hattusa during the 13th century BC. After the collapse of the Hittite New Kingdom during the more general Late Bronze Age collapse, Luwian emerged in the early Iron Age as the main language of the so-called Syro-Hittite states, in southwestern Anatolia and northern Syria.

Hittite is the modern scholarly name for the language, based on the identification of the Hatti (Ḫatti) kingdom with the Biblical Hittites (Biblical Hebrew: *חתים Ḥittim), although that name appears to have been applied incorrectly: The term Hattian refers to the indigenous people who preceded the Hittites, speaking a non-Indo-European Hattic language.

In multilingual texts found in Hittite locations, passages written in Hittite are preceded by the adverb nesili (or nasili, nisili), "in the [speech] of Neša (Kaneš)", an important city during the early stages of the Hittite Old Kingdom. In one case, the label is Kanisumnili, "in the [speech] of the people of Kaneš".

Although the Hittite New Kingdom had people from many diverse ethnic and linguistic backgrounds, the Hittite language was used in most secular written texts. In spite of various arguments over the appropriateness of the term, Hittite remains the most current term because of convention and the strength of association with the Biblical Hittites. The endonymic term nešili, and its Anglicized variants (Nesite, Nessite, Neshite), have never caught on.

Hittite is one of the Anatolian languages and is known from cuneiform tablets and inscriptions that were erected by the Hittite kings. The script formerly known as "Hieroglyphic Hittite" is now termed Hieroglyphic Luwian. The Anatolian branch also includes Cuneiform Luwian, Hieroglyphic Luwian, Palaic, Lycian, Milyan, Lydian, Carian, Pisidian, Sidetic and Isaurian.

Unlike most other Indo-European languages, Hittite does not distinguish between masculine and feminine grammatical gender, and it lacks subjunctive and optative moods as well as aspect. Various hypotheses have been formulated to explain these differences.

Some linguists, most notably Edgar H. Sturtevant and Warren Cowgill, have argued that Hittite should be classified as a sister language to Proto-Indo-European, rather than as a daughter language. Their Indo-Hittite hypothesis is that the parent language (Indo-Hittite) lacked the features that are absent in Hittite as well, and that Proto-Indo-European later innovated them.