|Race||Dweller in the Dungeon Dimensions|
|Occupation||demonic entity and Unseen University final exam question|
|Physical appearance||indescribably foul|
|Residence||the Dungeon Dimensions|
|Death||"immortal", in the same conditional way Gods and demons are practically immortal|
A feared denizen of the Dungeon Dimensions, whose distinctive cry of YerWhat!Yerwhatyerwhatyerwhat! in the psychic space has provoked an attack of brown trousers in any foolhardy wizards daft enough to get within hearing distance.
The name is a reference to H. P. Lovecraft's Yog-Sothoth, The Lurker at the Threshold, The Key and the Gate, The Beyond One, Opener of the Way, The All-in-One and the One-in-All.
The very name Yog-Sothoth may be a rough transliteration of the Arabic phrase "Yaji Ash-Shuthath," meaning "There is no peace at the gates".
Additionally, in Roundworld English, "Yob" means a rowdy, aggressive, or violent young man (hence the "Yerwhatyerwhatyerwhat!" loutish football hooligan's cry), and "Sod off" is effectively the same as "Screw You". So, presumably, an all-round unpleasant kind of being.