Robert Karl Friedrich Gysae (14 January 1911 – 26 April 1989) was a German U-boat commander in the Kriegsmarine during World War II.

Gysae joined the Reichsmarine in 1931 and served on torpedo boats before transferring to the U-Bootwaffe ("U-boat force") in April 1940.

On 28 November 1942 off the coast of Natal Province, Gysae sank the 6,796 ton British troop ship RMS Nova Scotia with three torpedoes.

The BdU notified the Portuguese authorities, who sent the frigate NRP Afonso de Albuquerque from Lourenço Marques to help.

In April 1945, during the last month of the war, Gysae commanded the Marinepanzerjagd-Regiment 1, a naval anti-tank regiment.