Oscar Reutersvärd (1915 – 2002) was a Swedish graphic artist, who in 1934 pioneered the art of 3D drawings that may initially appear feasible yet cannot be physically constructed. He is sometimes described as "the father of the impossible figure"

Born in 1915, Stockholm, Sweden, he reportedly suffered from dyslexia and had difficulty estimating the distance and size of objects. But his family was artistic, and encouraged his painting and sculpture efforts at home. Reutersvärd's originality appeared early in his career—at the age of 18. In 1934, the school student created a figure, the “impossible triangle”, composed of a series of cubes in perspective. "The triangle at first seems like the simple geometrical shape with which all schoolchildren are familiar. However, as the eye tries to follow its outlines, the triangle abruptly becomes a dizzying experience as its bottom link plays havoc with the brain's intuitive knowledge of physical laws." according to World of Mathematics, 2006, published by Thomson Gale. This very triangle was chosen in 1982 by the government of Sweden as the subject of a postage stamp. In 1937, he created his first impossible stairs, and the concept that would lead to the impossible fork. Subsequently, he focused on academics. In 1958, he read the now classic article by Lionel and Roger Penrose on impossible objects, which included the triangle and staircase that the British father and son team had developed independently. One artist inspired by the Penrose article was M.C. Escher—who produced two prints of impossible buildings in 1961 and 1962. The application of the concepts he originated over 20 years prior, by serious mathematicians and artists, rekindled Reutersvärd's interest. He would create his figures with India ink on Japanese rice paper, drawing freehand, without a ruler. He generally used Japenese perspective " where all parallel lines remain parallel and do not meet at points of visual convergence." The shaky lines, often exacerbated by working on the train ride between Stockholm and Lund, is obvious in some of his pictures. Figures were frequently colored with Japanese colored chalk. In comparing his work to that of the much more famous artist of the impossible, M.C. Escher, it can be observed that Escher builds inhabited worlds around impossible objects, whereas Reutersvärd's designs generally consist of pure geometric forms. In the late 1960s, several books were published featuring his work, and he attracted a following, with many international gallery exhibitions. Through the 1980s and 1990s, he continued to develop impossible figures. Today both mathematicians and psychologists use his drawings as templates for studying visual perception.