Thomas Holtan was a visual artist born in Sandefjord in 1887. At an early age the family moved to Tjøme, where his father became manager of old Consul Bryde's estate "Nedre Haug" and the artist-to-be first began as a clerk in Tønsberg. But at the age of 20 he went to Oslo to become a painter. He belonged to the first batch of students at the National Academy of Arts. From 1907–1909 he was a pupil of Harriet Backer and Erik Werenskiold, and from 1909–1912 a student at the State Academy of Fine Arts in Kristiania under Christian Krohg and Halfdan Strøm.
     At age 23 Holtan made his debut at The Norwegian State Art Exhibition in 1910 with a realistic girl portrait in full figure titled "Young Lady". He managed to get one scholarship of NOK 300 from the King, which furthered his education.

     Together with artist Guido Schjølberg, he went to Paris and Spain in 1912. Influenced by the modern art he saw, his form became looser strokes, broad and decorative and with use of freer color. Of great importance to his design language was his friendship with the artist Kristen Holbø. The artist held his first solo exhibition in Blomqvist Kunsthandel in 1913.
    From 1920 he painted mainly in Tjøme, but also in Gudbrandsdalen, Lillehammer and Tønsberg. A decoration he executed at Tønsberg's Blad canteen in 1931 depicts the work of printmaking, distribution and newspaper readers. The style is named "simplistic realism".

     In 1920 he earned enough to buy himself a house cottage on Engø on Tjøme, with a view of Holtekjærkilen. From there he painted several of his famous pictures, among others "Grågåstrekk" in 1936, a picture that is reproduced in the Illustrated Norwegian Art Encyclopedia. In the 1920s and 1930s the artist worked for Tønsbergs Blad as a newspaper cartoonist. He also provided humorous drawings for the publications "Signs of Time" and "World Walk".

     In his 30s, new impulses made him seek a stricter form. He painted strongly simplified mood landscapes in a muted dark color palette. After the Second World War he worked for a short period in an abstract form of language. In 1933 he held an exhibition at the Art Association in Oslo and participated in the National Gallery's retrospective exhibition of Norwegian art in 1940.

     The artist contributed works to more than 20 group exhibitions in Oslo between 1910–1951. He also held solo exhibitions at Hotel Atlantic in Sandefjord in 1913 and 1918, at Blomqvist Kunsthandel in Oslo in 1913 and 1921, the Oslo Art Association in 1933, the Tønsberg Art Association in 1947, Fredrikstad Art Association in 1948, at the Vestfold County Museum in Tønsberg in 1955, and a Memorial exhibition at the Sandefjord Art Association in 1977.
     His ornaments and works in public collections include Tønsberg's Blade canteen (oil on canvas, 1931), portraits in Sem Sparebank Tønsberg, Jacob Breda Bull Museum, Upper Rendal Tønsberg, and Sandefjord art associations.