Collidus the Warp-Watcher
Collidus the Warp-Watcher is a demon eye-ball thing. He is located in Shadowmoon Valley. He has 3 different spawn areas and 3 different paths in Shadowmoon Valley. Most of these locations aren't by anything special so finding him may be a bit tricky. For Collidus you'll want to make your macro /target Collidus .
The best place to hang out and farm for Collidus is the southern most path. If you're a skinner, you may find better money by the Death Forge. Regardless, every 10-15 minutes mount up and head to each of these 3 locations, spam your macro and fly over head. It shouldn't take too long to find him.
Collidus the Warp-Watcher Spawn Locations