Theobald Rehbaum (17 August 1835 – 2 March 1918) was a German violinist, librettist and composer, especially of operas.
Born in Berlin, Rehbaum grew up there and sang as a boy in the Royal Domchor [de].
He studied violin and composition with Friedrich Kiel, and composition also with Hubertus Rios.
Rehbaum composed several operas and choral works, but was more successful as a librettist, writing librettos for Bernhard Scholz.
He also wrote a Bratschenschule zum Selbstunterricht für Violinisten (viola method for self-instruction for violinists) and an autobiography titled Erlebtes und Erstrebtes.