Dunash ben Labrat (920-990) was a medieval Jewish commentator, poet, and grammarian of the Golden age of Jewish culture in Spain and a student of Rabbi Saadia Gaon. He was born in the city of Fes, Morocco.

Dunash was an outstanding Hebrew poet, who first introduced Arabic meter into Hebrew poetry. Traditional Arabic poetry was built on interspersing long and short vowels. In contrast, Hebrew distinguishes between the quality of the vowels, rather than their length. Dunash's innovation came in drawing a parallel between the šəwâ (ə) and ḥāṭēp̄ (ĕ/ă/ŏ) and the Arabic short vowels (i/a/u), so as to create a new Hebrew meter. This meter formed the basis for all subsequent medieval Hebrew poetry. At the time, however, it opened him up to severe criticism, particularly among the students of Menachem ibn Seruq , that he was corrupting the Hebrew language by introducing Arabic forms, and changing traditional biblical styles to conform to Arabic meter and rhyming schemes. For instance, in his classic poem "Dror Yikra", he begins the second line: Ne'im shim'chem ("pleasant is your name"), with a modifying form of the noun "pleasant," where properly it should be na'im.

As a grammarian, Dunash's major work was a book attacking Ibn Seruq and his Mahberet (Notebook) for violating religious standards and opposing the teachings of the sages. He dedicated his work to the Exilarch, Hasdai ibn Shaprut. In his book, he was the first Hebrew grammarian to distinguish between transitive and intransitive verbs, the first to list verbs by their three-letter roots in the Paal construction, and the first to distinguish between "light" and "heavy" roots. He also condemned ibn Seruq for failing to see the relationship between Hebrew and Arabic. Dunash also wrote a book containing 200 reservations about the teachings of his old mentor, Saadia Gaon.

The students of ibn Seruq responded with a scathing attack on Dunash, condemning him for using Arabic meter and grammar in studying the Hebrew language, as well as on issues of Jewish philosophy about which they were at odds. Abraham Ibn Ezra also wrote a response to Dunash, in defense of Saadia Gaon. These challenges were met by Yehudi ben Sheshet , one of Dunash's students, who wrote a work in defense of his master that bitterly attacked all of his detractors.

The debates between Dunash and others were finally decided in the centuries after his death by Rabbeinu Tam, a grandson of Rashi, who attempted to judge between the two schools of thought, and by Rabbi Joseph Kimchi , father of the noted grammarian David Kimchi (RaDaK), who supported Dunash's positions. Nevertheless, many of the issues raised by Dunash have yet to be resolved today. Dunash is remembered as a poet and a grammarian who uncovered many of the major problems of Hebrew grammar.