Este é o " The Unlikely Ones da Mary Brown.
O enredo e os personagens são exatamente como você descreve:
In a dank cottage, 5 unlikely heroes are enslaved by an evil witch through very painful pebbles embedded in their flesh. They are Thing, a twisted girl deemed so hideous that she always wears a mask, Corby, the black crow, Puddy, the toad, Moglet, the timid kitten, and Pisky, the golden fish. They have no memory of their past and have learned over time to communicate amongst themselves.
When the villagers band together to burn the witch, our heroes escape and set out to solve the mystery of how to remove the pebbles that are causing them such agony. Along the way they meet two others harmed by the witch. The first is a hornless unicorn, whose whose horn was destroyed and companion was slain by the witch. The second is a knight cursed by the witch because he spurned her. His curse is to have rusty armor, a blunt sword, and all desire unfulfilled until he weds the ugliest creature in the land.
Note também que a edição de 1990 do Reino Unido realmente teve uma capa vermelha com uma ilustração:
