Thor Hiorth Schøyen (May 1, 1885 – June 6, 1961) was a Norwegian entomologist.
He became the curator of the Oslo Zoological Museum in 1908.
Later, in 1913, he became the government entomologist at the Norwegian Plant Protection Office (Statens plantevern), a position that he held for 42 years.
Schøyen taught at the Norwegian College of Agriculture from 1910 to 1950.
He was also a central figure in the Norwegian Entomological Society.
He received the King's Medal of Merit in gold in recognition of his work.Thor Hiorth Schøyen became interested in nature and insects at an early age, and he studied zoology at the University of Oslo.
He was described as "...
a quiet man, gracious and helpful, without prejudice.
He had diverse interests and was a gentleman throughout his journey." He was the son of the entomologist Wilhelm Maribo Schøyen.