Waldemar Lorentzon (1899–1984) was a Swedish painter and one of the founders of the influential artist group Halmstadgruppen. He was born in Falkenberg and educated at the Valand Painting School and the Académie Moderne in Paris, where he was strongly influenced by the development of modern art.

Lorentzon's art is characterized by a strict, surrealistically colored style with a clear sense of form and architectural balance – often in dialogue with dreams and the subconscious. Together with Sven Jonson and Erik Olson, among others, he contributed to introducing modernism into Swedish art life during the first half of the 20th century.