Franz Joseph Weissmann (Knittelfeld, Austria, 1911 – Rio de Janeiro, RJ, 2005) was a sculptor, draftsman, painter, and teacher. 

He moved to Brazil in 1921. In Rio de Janeiro, between 1939 and 1941, he attended courses in architecture, sculpture, painting, and drawing at the National School of Fine Arts (Enba). From 1942 to 1944, he studied drawing, sculpture, modeling, and casting with August Zamoyski (1893-1970). In 1945, he moved to Belo Horizonte, where he taught private lessons in drawing and sculpture. Three years later, Guignard (1896-1962) invited him to teach sculpture at the Escola do Parque, which later became known as the Guignard School. Initially, his work was based on figuration. From the 1950s onward, he gradually developed a constructivist approach, emphasizing geometric forms, subjecting them to cuttings and folds, and using sheets of iron, steel wires, and aluminum in rod or sheet form. He joined the Grupo Frente in 1955. 

No ano seguinte, voltou a residir no Rio de Janeiro e participou da Exposição Nacional de Arte Concreta, em 1957. Foi um dos fundadores do Grupo Neoconcreto, em 1959. Nesse ano, viajou para a Europa e o Extremo Oriente, retornando ao Brasil em 1965. Na década de 1960, expôs a série Amassados, elaborada na Europa com chapas de zinco ou alumínio trabalhadas a martelo, porrete e instrumentos cortantes, alinhando-se temporariamente ao informalismo. Posteriormente, voltou a aproximar-se das vertentes construtivas. Nos anos 1970, recebeu o prêmio de melhor escultor da Associação Paulista de Críticos de Artes (APCA), participou da Bienal Internacional de Escultura ao Ar Livre, em Antuérpia, Bélgica, e da Bienal de Veneza. 

He created monumental sculptures for public spaces in various Brazilian cities, such as in Praça da Sé, São Paulo; Parque da Catacumba, Rio de Janeiro; and the Palácio das Artes, Belo Horizonte.