Ogres were monstrous and destructive creatures of legend and folklore. In fact, it is doubtful whether Ogres ever existed in Middle-earth.
During the Riddle-game with Gollum, Bilbo Baggins in his attempt to solve Gollum's fifth riddle, he sat thinking of all the horrible names of all the giants and ogres he had ever heard told of in tales.
No ogre is ever mentioned in the annals of the Elder Days and none played any role in the wars and battles. It is entirely possible that they were a mythical race.
It is also possible that Ogre is just another name for the Trolls.
Other versions of the legendarium
Tolkien mentioned once more ogres out of context in his analysis of the name Ettendales in Guide to the Names in The Lord of the Rings: "This is meant to be a Common Speech (not Elvish) name, though it contains an obsolete element eten 'troll, ogre'."