The caspase family of proteases function by cleaving at aspartyl residues directed by a cysteine in the active site. They are notable for their essential role programmed cell death, in which the their activation cascade results in degradation of cellular components. Caspase deficiency is implicated in tumor development whereas overactivation of certain caspases has been observed in neurodegenerative diseases. In studying the different members of this family, as well as processes involved with cell death or proliferation, many synthetic inhibitors blocking caspase activity have been developed. Peptide-based compounds are perhaps the most widely used, with versions targeting both specific or broad-spectrum caspases. Others that are more specific have found potential use in therapeutic applications.