Glatz, Silesia – 7 October 1945 Dresden) was a German ornithologist and bird illustrator.
In 1887, Bruno Geisler began collecting birds in Ceylon and Java with his brother Herbert.
The bird skins collected by Bruno and Herbert were studied by Adolf Bernard Meyer then a professor at the Dresden museum.
He became also well known for the bird plates in The birds of Celebes and the neighbouring islands by Adolf Meyer and Lionel William Wiglesworth published in Berlin by R. Friedländer in 1898, Anton Reichenow’s Die Vögel Afrikas Vols 1-3 published by J. Neuman in Neudamm between 1897 and 1905 and in the new Naumann's, Naturgeschichte der Vögel Mitteleuropas published in 1900–1905.
Frogs Oreophryne geislerorum and Dendropsophus giesleri are named after him, the first together with his brother, Herbert Geisler.