Johann Georg Repsold (September 19, 1770 – January 14, 1830) was a German astronomer.

He joined the fire brigade of Hamburg in 1799. In 1802 he began building a private observatory, and collaborated in astronomical observations with Heinrich Christian Schumacher. However the observatory was destroyed in the Napoleonic Wars in 1811. In 1825 a new observatory was completed at Stadtwall, and Repsold became the director, supplying the instruments at his own expense with other funding from the city of Hamburg.

In 1830 he died in the line of his firefighting duties. The expense of running the observatory was taken over by the local government, and the new director was Carl Ludwig Christian Rümker. Repsold's observatory was demolished upon the completion of a new observatory, the modern Hamburg Observatory at Bergedorf, between 1906 and 1912. The site is now occupied by the hamburg museum

The crater Repsold on the Moon is named after him, as is the asteroid 906 Repsolda.