Ghouls were a playable race in version 0.202 of Mount&Blade.
Ghouls are actually normal people that have been turned to slaves by a Necromancer in a quest where you have to receive the hand of a god.
Like the Undead, Ghouls may only appear on the map when a quest is activated. Unlike the Undead, you can also choose to be a Ghoul when creating your character. To activate this quest, you need to enable cheats.
- Press Crtl-F for all locations to show up.
- Go to Khergit Camp.
- Talk to the Uruzuge and her father.
- Her father will tell you to ask Akhad Thell for something to heal her.
- Go to Serrepa and talk to Akhad. And so the quest begins.
The reason for their removal was the developers thought the idea was even more off topic than the Undead. They can be found in troops.txt and in factions.txt.