Carl Ernst Albrecht Hartwig (14 January 1851 in Frankfurt – 3 May 1923 in Bamberg) was a German astronomer.
He discovered a new star in M31 (the "Andromeda Nebula") on 20 August 1885. This object was designated as supernova "S Andromedae". He observed the 1882 transit of Venus in Argentina. During the 1883 observation campaign of comet 6P/d'Arrest he found five NGC objects working at the Strasbourg Observatory. In 1874 he became assistant at Strassburg Observatory, 1884 astronomer at Dorpat Observatory and 1887 director of Bamberg Observatory.
The French Academy of Sciences awarded him the Prix Valz in 1902 for his heliometer observations and work on variable stars.Craters on the Moon and on Mars were named in his honor.