The Penrose triangle, also known as the Penrose tribar, or the impossible tribar,[1] is a triangular impossible object. It was first created by the Swedish artist Oscar Reutersvärd in 1934. Independently from Reutersvärd, the psychiatrist Lionel Penrose and his mathematician son Roger Penrose devised and popularized the triangle in the 1950s, describing it as "impossibility in its purest form". It is featured prominently in the works of artist M. C. Escher, whose earlier depictions of impossible objects partly inspired it.