Alligatorium is an extinct genus of atoposauridcrocodylomorph. Alligatorium remains have been found in Germany and Mongolia. There are several species included within the genus. The type species is A. meyeri, named in 1871. Other species include A. franconicum, named in 1906, and A paintenense, named in 1961. A franconicum is considered a nomen dubium. A paintenense is likely to be closely related to the familyGoniopholididae and not a member of the Atoposauridae. Another species, A. depereti, was named in 1915, but has since been reassigned to its own genus, Montsecosuchus.