Theodor Matthei (January 31, 1857 in Marburg – March 6, 1920 in Kassel) was a German painter, member of the Willingshausen painters’ colony, grandson of Johann Friedrich Matthei.
Matthei studied at the Kassel Academy with Louis Kolitz and Hermann Knackfuss. From 1881 to 1886, while he was still studying, he and his classmates Jean Konrad Bohlender and Heinrich Otto visited the painters’ colony in Willingshausen in the summer months, where he also became friends with Adolf Lins and Emil Zimmermann.
Matthei initially painted landscapes with staffage. Later he created genre pictures from life in Schwalm. In 1887, he spent a few months in Munich. Around 1900 he visited Italy and painted sunny landscape studies from around Rome.