Antrodemus ("chamber bodied") is a dubious genus of theropod dinosaur from the Upper Jurassic, probably the Morrison Formation, of Middle Park, Colorado.

The first described fossil specimen was a bone obtained secondhand by Ferdinand Vandeveer Hayden in 1869 (original discoverer unknown).

[1] Hayden sent his specimen to Joseph Leidy, who identified it as half of a tail vertebra, and tentatively assigned it to the European dinosaur genus Poekilopleuron as Poicilopleuron [sic] valens, based on the shared presence of a large medullary cavity.

[4] Subsequent authors have agreed with this assessment and have considered Antrodemus a nomen dubium.

For years, that skeletal mount was presented to the visitors under the taxonomic name Antrodemus, before the specimens from the Cleveland-Lloyd Quarry were attributed to Allosaurus.