Cannibalism, the killing and consumption of conspecific individuals, is a common and widespread phenomenon in the animal kingdom. Cannibalism in phytoseiid mites has been known for decades but until recently reports were mainly observational and experimental data were lacking. Recently, diverse aspects of cannibalism, such as life stage-related cannibalism and preference, nutritional benefits, the role of diet specialization, species discrimination, and kin discrimination were assessed and compared within and among diverse phytoseiid species. As a result, species of the family Phytoseiidae provide a rather well studied group with respect to cannibalism at the individual level. The present review aims at summarizing and canalizing the wealth of recent experimental data on cannibalistic phytoseiid mites and seeks to emphasize and discuss the behavioral and ecological significance of cannibalism. In an ideal case, it will stimulate studies on topics related to cannibalism that are currently underrepresented such as the consequences of cannibalism for population dynamics and species composition in a given habitat. Partitioned in six sections, the key determinants of cannibalism in phytoseiid mites are treated by extracting features that are common among species and, where applicable, by indicating the circumstances that minimize the costs and maximize the benefits of cannibalism.