Agnes Heiberg-Mannheimer was a Swedish-Norwegian painter.

She was the daughter of Otto Mannheimer and Charlotte Abrahamson and from 1922 married to the artist Jean Heiberg. Heiberg studied under Birger Simonsson at the Valand School of Painting in Gothenburg and at the Wilhelmson and Grünewald Schools of Painting in Stockholm, as well as under Henrik Sørensen in Oslo and during several study trips to France. She exhibited separately at the Kunstnerforbundet in Oslo in 1931 and participated in the Oslo Autumn Exhibition in 1933.

In her early art she was influenced by the Gothenburg artists Birger Simonsson and Gösta Sandels, while towards the end of her life she was influenced by the austere Norwegian painting, in which she displayed a coloristic talent. Her art consists of still lifes, portraits, figures, flowers and landscapes with motifs from Skåtøy near Kragerø and Holmsbu. Heiberg is represented at the Gothenburg Museum of Art. Several memorial exhibitions have been held with her art, the first of which was in 1935 at Göteborgs konsthall, which showed works by Charlotte Mannheimer and Heiberg, who both died in 1934. Galleri God Konst in Gothenburg showed a selection of her work in 1947 and Kunstnerforbundet in Norway showed a selection of her watercolors painted 1917-1934 in 1964.