Ogres

Ogres were a race mentioned only fleetingly, once, in The Hobbit.

Overview
Ogres were mentioned in the context of the Riddle Game between Bilbo Baggins and Gollum. After Gollum asks a riddle about what "ruins kingdoms" and "beats tall mountains down", Bilbo tries to think of all the giants and ogres that he's heard of. None of them, however, are horrible enough to meet the description of the riddle.

It is possible that ogres were a mythical monster in Hobbit folklore rather than an actual race. It is also possible that, like Giants, they were simply dropped as Tolkien expanded Middle-earth and the related cosmology.