Metacaspases are cysteine proteases, found in every group of organisms except metazoa. They are structural orthologs of caspases, which orchestrate apoptosis in metazoa. Like caspases (cysteine-dependent aspartate-directed proteases), paracaspases, and orthocaspases, metacaspases are class C14 proteases, with a hemoglobinase fold and a catalytic cysteine residue. However, metacaspases cleave after arginine or lysine rather than aspartate, prompting calls to rename them. Furthermore, most metacaspases are activated by calcium; they do not target the same range of proteins as caspases, and they tend to cut target proteins multiple times rather than at a single, canonical site. The Candida albicans metacaspase Mca1p mediates cell death in response to various stresses but also has pro-life functions, such as clearing protein aggregates and extending lifespan. Many plant and protist metacaspases lack cell-death roles and instead mediate development, differentiation, and immunity. This article highlights the phase-dependent reversal of Mca1p’s effects on susceptibility to acetic acid, hydrogen peroxide, and amphotericin B, as well as on C. albicans virulence in Galleria mellonella larvae. This reversal of metacaspase function indicates the protein’s dual nature and the conditions that drive the switch from its pro-survival to its pro-death role.