Apoptosis, or programmed cell death, is the mechanism by which cells die either physiologically or pathologically. A vast research in apoptosis has advanced our understanding of basic physiological and pathological processes occurring in cells, organs and organisms, and its role in a number of diseases. These new advanced understandings are playing a major influence in drug discovery and the introduction of new therapies that target this cell death process. These two thematic volumes 125 and 126 of the Advances in Protein Chemistry and Structural Biology focus on apoptotic responses in numerous conditions - from bacterial and parasite infections to pathological states such as oxidative stress, pulmonary hypertension, different cancer types, etc. Finally, therapeutic strategies for targeting apoptosis are also discussed.