The purpose of this thesis is to undertake a thorough analysis of Sam Shepard's approach to the character in a selection of his plays from the 1970s. Instead of approaching characters as compact entities with fixed character features the thesis focuses on their instability and changeability and attempts to ascribe characters' transformations to dynamic non-subjective forces and to identify ego-loss as a partially liberating process that nonetheless confronts the characters with the unknown and is accompanied by fear of self-loss. From the theoretical vantage point of the collaborative writings of Gilles Deleuze and Félix Guattari, the thesis equates the transformations of Shepard's characters and their inability to locate the "self" with the schizophrenic experience. As a musical genre based on variability, jazz, as well as its inherent form of expression, improvisation, are utilized as points of departure in the analysis of characters' instability in plays Suicide in Bb and Angel City. Furthermore, in Angel City, the phenomenon of film in the USA and the desire for success and fame intensified by it are perceived as instruments of manipulation and illusion, which characters easily succumb to and which severely alter their sense of reality. Moreover, the environment of filmmaking is introduced as a...