Karel Johan Gustav Hartlaub (8 November 1814 - 29 November 1900) was a German physician and ornithologist.

Hartlaub was born in Bremen, and studied at Bonn and Berlin before graduating in medicine at Göttingen. In 1840, he began to study and collect exotic birds, which he donated to the Bremen Natural History Museum. He described some of these species for the first time. In 1852,