Jan Josef Ignác Brentner (Johann Joseph Ignaz, surname also spelled Brenntner, Brendner, Brendtner, or Prentner; 3 November 1689 – 28 June 1742) was a Bohemian composer of the Baroque era.
Brentner's opuses 1 and 3 are collections of sacred arias for voice, strings, and continuo, Harmonica duodecatomeria ecclesiastica (1716) and Hymnodia divina (1718 or 1719).
Although a great many of Brentner's works are known to be lost, a scattering of manuscript copies survive throughout the Czech lands and a large number of them are located in the Music Archive of the Bendiktinerstift in Göttweig, Austria.
Registries of lost collections belonging to provincial churches in central Europe bear witness to Brentner's works that are no longer extant.
Although Brentner has never been a famous name, his music has proved enduring—it was still being performed in Prague and Vienna (Hofkapelle) in the mid-nineteenth century, and they have never stopped playing it in Bolivia.