Compendium One contained an article on The Mark of Chaos that featured 3 Chaos monsters, Ngaaranh Spawn of Chaos, Zygor Snake Arms and Leaping Slomm Two Face.  Slomm and Ngaaranh were later released as part of the c27 Chaos Monsters range. There is also an unreleased version of the  Leaping Slomm that is closer in appearance to the illustration, but apparently would not cast, making it an extremely rare item.

Ngaaranh Spawn of Chaos

Ngaaranh was once a Harpy, but centuries of unspeakable deeds serving in the marauding pack of the vile Chaos Godling known only as Kwa (and those who are wise speak that name only in whispers) have twisted her body and soul to the shapes of Chaos

Zygor Snake Arms

Zygor the Night Goblin has been determined to have Chaotic Attributes.  Zygor has three tentacle-like prehensile tails instead of arms and that his face is situated in the middle of his body.

Leaping Slomm Two Face

As Trolls are Creatures of Chaos, Slomm the Troll gets powerful legs, great fangs, multiple heads, bestial face (Of a Walrus). Also pictured here is the unreleased version – you can see how close it is to the original drawing.