Fredrik von Sydow (1908 – 7 March 1932) was a law student who became known for the "Sydow murders" in Stockholm and Uppsala on 7 March 1932.

Fredrik von Sydow came from an upperclass family in Stockholm and studied Law at Uppsala University.

On March 7, 1932, his father Hjalmar von Sydow, who was a conservative member of parliament and the managing director and chairman of the Swedish Employers' Federation and two maids employed in the household were found dead in the family residence in Stockholm, all bludgeoned to death with an iron bar. Even though the police soon came to suspect the son, Fredrik, it took a few hours before they were able to locate him.

Fredrik von Sydow had taken a taxi with his wife Sofie to Uppsala, where they entered the restaurant of Hotel Gillet and ordered Champagne, caviar and oysters. When the police eventually arrived to the restaurant, Fredrik von Sydow took up a gun and shot his wife and himself to death.

The motives of Fredrik von Sydow have never been clarified, but the relative prominence and public position of the family made the murders a significant scandal and the object of much speculation. The writer Sigfrid Siwertz wrote a play, Ett brott ("A crime", 1933) based on the murders, on which a 1940 film of the same name was based.