Alligatorium is an extinct genus of atoposaurid crocodylomorph from Late Jurassic marine deposits in France.

The type species is A. meyeri, named in 1871 from a single specimen from Cerin, eastern France.

Two more nominal species, A. franconicum, named in 1906, and A paintenense, named in 1961, are based on now-missing specimens from Bavaria, southern Germany, and were synonymized into a single species, for which A. franconicum has priority.

[1] A 2016 review of Atoposauridae removed A. franconicum from Alligatorium and placed at Neosuchia incertae sedis.

[2] Alligatorium depereti, described in 1915, was reassigned to its own genus, Montsecosuchus, in 1988.