This thesis examines pain in performance art and, as the subtitle suggests, it addresses notions of bearing witness by examining art practices that cross the boundaries of performance art, social practice, illness, activism, and other forms of confrontation with the male body. Bearing witness takes up ideas of witnessing as 'a collective sensorial practice of listening to bodies' , as well as concerns with 'seeing how seeing takes place,' which allows possibilities of moving beyond an audience's role as witnesses and drawing attention to the very conditions of witnessing itself. To explore these ideas, this thesis analyses the work of three artists - Ron Athey, Martin O'Brien and Ulay - exploring ideas of how witnessing pain operates through three different sites: audiencing, curating and documenting. This analysis demonstrates the creative and political potential that a range of sites and ways of witnessing pain offers audiences, artists, and curators. It explores how pain serves as a critical tool, whether functioning metaphorically, conceptually, or literally, to understand how the body of the artist tells of their most intimate experiences, thus requiring that we once again revisit the place and potency of the body in performance art and its intersections within a range of identities. By considering the work of these three cross-generational artists, and with the varying pain actions they deploy, this thesis extends and develops interdisciplinary work on performing bodies, pain, and witnessing.