Tor Tønsberg (born 1948 in Oslo) is a Norwegian lichenologist who has made significant contributions to the taxonomy, chemistry, floristics, and phytogeography of lichens and lichenicolous fungi.

Summers at his family's farm, Myrvang, in Majavatn in Grane Municipality in northern Norway, also played a significant role in fostering his love for the natural world.

He completed his degree in 1975 with a floristic and phytogeographic study of Børgefjell National Park, under the supervision of Professor Hildur Krog, a prominent Norwegian lichenologist.

[2] In 1976, Tønsberg was appointed as a scientific assistant at the University of Trondheim, where he investigated the lichen-rich humid coastal spruce forests of Central Norway.

He focused on the study of sterile crustose lichens, earning his doctorate in 1996 with a thesis praised by Peter Wilfred James as "a Cadillac monograph".

[3][4] Tønsberg has enriched herbaria with approximately 50,000 specimens and described numerous taxa, including the genus Japewia and Toensbergia, the latter named in his honour for his contributions to the study of sterile lichens.