This article presents a contemporary clinical reappraisal of Mario-Fiacca, a historical Italian case originally described by Beppino Disertori in 1939. Mario C., a man with post-encephalitic parkinsonism, repeatedly entered states in which he became Fiacca, the clown identity assigned to him after childhood abduction, maltreatment, sale to an equestrian circus, and forced training. In these states, the hospital ward was transformed into the circus, memory became state-dependent, and the rigid post-encephalitic body recovered striking forms of movement, analgesia, and performative agency. Drawing on Disertori’s clinical record and later historical commentaries, this article reconstructs Mario’s life history, clinical manifestations, treatment, and outcome, and then offers a contemporary formulation grounded in trauma-related and attachment-informed models of dissociation. Fiacca is conceptualized as a dissociated self-state in which traumatic separation and renaming, coerced adaptation, attachment loss, post-encephalitic neurological vulnerability, and suggestive processes became organized within a separated mode of existence. The case remains clinically important because it shows how dissociation may involve identity, autobiographical memory, perception, and the lived body within the same state-dependent organization.