My contribution attempts to investigate the intertwining of art and life in Wolfgang Hildesheimer’s Marbot as a manifold process that touches upon the notions of authorship, authenticity, legitimation and fictionality. Hildesheimer himself stated that in Marbot he was biographer and autobiographer at the same time. When the biographical text cannot refer to an extratextual reference whose factual basis stands the test of truth beyond any reasonable doubt, the authenticity of the main character of a mock-biography lies precisely in its fictionality.