This is a study of the tragic in modern theater in the works of Eugene O'Neill and Nelson Rodrigues. Why Eugene O'Neill and Nelson Rodrigues? Firstly, because they are two playwrights I admire and have been interested in for many years. Secondly, specifically considering the subject of this work, they are authors who, for the first time in the dramaturgy of their countries, presented an original and revolutionary formulation of the tragic, transforming the archaic structures of the theater in force at the time of the premieres of their first plays. This is a work of great interest to lovers of theater, especially the works of these two great writers.