Hans Olaf Halvor Heyerdahl (8 July 1857, Smedjebacken, Sweden - 10 October 1913, Oslo) was a Norwegian Realist painter.
He was the son of Halvor Heyerdahl (1825-1900), a prominent engineer. In 1859, the family moved to Drammen, where his father took up the joint posts of City Engineer and Fire Chief.
He began his education with the intent of following in his father's footsteps, but soon discovered that he was more attracted to drawing and art.
In 1873, he entered the Norwegian National Academy of Craft and Art Industry and studied under Peder C. Thurmann, a landscape artist trained in Dusseldorf.