Shadow of Night
Most everyone speaks the Common tongue, throughout the known world.
Many Northmen, especially those in the wastelands, speak a vaguely-related dialect called Northtongue, which also combines elements of the Amaiss private language.
The elves and dwarves each have their own language.
If the gnomes have one, no one else has ever heard it.
The ogre language, for the few who still speak it, is called Ogron.
Many of those under the dominion of the Shadow speak a gutteral language called the Dark Speech by everyone else.
Draconic is the language of both dragons and dragon-men.
Also of note is Ancient Doron, a language that no one really speaks any more, but can still be found inscribed on many an ancient ruin, as well as in the elements of various proper names.