Per Olov Jansson (b. 22 April 1920 Helsinki, Finland) is a Finnish photographer. He is the son of artists Viktor Jansson and Signe Hammarsten-Jansson, and the brother of writer Tove Jansson and cartoonist Lars Jansson. His photography has appeared in books by Tove Jansson including An Unwanted Guest (1980) and Anteckningar från en ö (1993), and Tove's 1971 novel, Lyssnerskan is dedicated to him. He is also responsible for a great number of photos of his sister.