This list of prehistoric malacostracans illustrates the genera from the fossil record that have ever been considered to be malacostracans, a class of crustacean arthropod, excluding purely vernacular terms. The list includes all commonly accepted genera, but also genera that are now considered invalid, doubtful (nomina dubia), or were not formally published (nomina nuda), as well as junior synonyms of more established names, and genera that are no longer considered malacostracans. The majority of the genera are from the order Decapoda, for which a recent synopsis allows invalid names to be excluded.