瓦格纳低音号（英文：Wagner tuba）是一种标准管弦乐团里不常用到的铜管乐器。它是一种融合了长号与圆号各自的音色元素的乐器。

The Wagner tuba is an infrequently-used brass instrument that combines tonal elements of both the French horn and the trombone. Wagner tubas (or Wagnertuben) are also referred to as Wagner horns or Bayreuth tubas in English and as Bayreuth-Tuben or simply Tuben in German. The term Wagner tuba has been used in English since the 19th century and is standard today. Wagner's published scores usually refer to these instruments in the plural, Tuben, but sometimes in the singular, Tuba.