T cell antigens are important targets for cancer immunotherapy in the form of cancer vaccines or adoptive T cell therapy. These antigens are a result of tumorigenesis and can be either tumor-associated or tumor-specific, depending on their presentation on tumor and normal cells. Genetic aberrations that result in the formation of tumor-specific neoantigens in particular are of great interest for immunotherapy due to their potential, good tolerability, and lack of self-tolerance. Discovery of T cell epitopes for cancer immunotherapy is an active area of research, and new experimental and computational pipelines are constantly developed. In this chapter, we give an overview of some antigen- and T cell receptor (TCR)-centered discovery methods for the identification of T cell epitopes. Moreover, we talk about the characterization of identified tumor antigens in regard to important features of cancer immunotherapy.