Trachelosaurus is an extinct genus of lizard-like early archosauromorph reptiles in the family Trachelosauridae.

[1] It was originally described as a dinosaur[2] until it was redescribed as a "protorosaur" reptile by Robert L. Carroll in 1988.

[3] The type species, T. fischeri, was described by F. Broili & E. Fischer in 1917[2] based on remains found in the Solling Formation (Buntsandstein), Bernburg, Germany.

[4] A 2024 redescription identified Trachelosaurus as a long-necked and presumably aquatic reptile closely related to Dinocephalosaurus from the Guanling Formation of China.

However, the principle of priority instructs that the name Trachelosauridae, which was first erected as a monotypic clade for Trachelosaurus, should be used instead.