Hadar Jönzén was a visual artist born in Tyresö, Stockholm County in 1885 and part of the early Swedish avant garde. He spent most of his upbringing in Sundsvall together with his close friend Leander Engström, where they became frequent visitors to the art exhibitions organized in the area.

     He studied at the Technical School in Stockholm from 1904−1905 and at the Swedish Artist's Association School from 1906−1908. In the summer of 1906 Jönzén and Engström took their first trip to Stockholm where they came into contact for the first time with the Norrland painter Helmer Osslund. Osslund had appreciable influence on both of the younger artists. Later, in 1907, Jönzén, Engström and Osslund all won Lapland honors from the Swedish Artist's Association.
    Jönzén continued his studies in Paris from 1909−1911 and 1912−1914 and was for a time a pupil at Académie Matisse. In 1909 the artist showed works in Gävle at "Four Young Painters Exhibition" (fyra unga målares utställning) that included Engström and the artists Edith Granström and Gadde Strandberg. He exhibited at "The Young Ones" (De Ungas) third exhibition in 1911 at Hallins konsthandel in Stockholm along with his friend Engström. Later he made study trips to England in 1915 and to Spain from 1916−1920.

     He settled in Paris in 1920 but made frequent visits to Sweden. In 1924, Jönzén and other artists formed a group that called themselves the "Optimists", as a counter-reaction to the "Falangen" artist group led by Otte Sköld. The group debuted in 1926 in Stockholm, and later in Gothenburg and London. At the first exhibition at Liljevalchs Konsthall, artists included Greta Knudson, Ewald Dahlskog, Mollie Faustman, Carl Gunne, Bror Hjorth and Edvin Ollers.

     Later he exhibited at Göteborgs Konsthall in 1930 together with Carl Frisendahl and Lennart Blomquist. He was known for painting landscapes, street motifs and figure compositions.

     In 2014 Prins Eugens Waldemarsudde held an exhibition of artists that studied under Henri Matisse tltled," Inspiration Matisse!". Hadar Jönzén was included along with works by Isaac Grünewald, Sigrid Hjertén, Leander Engström, Nils Dardel, Maj Bring and Einar Jolin.
    The artist is represented in The Moderna Muséet in Stockholm, the National Museum in Stockholm, and the County Museum in Gävleborg.