Whiskers is a black and white cat, usually having wings.
It is the Eternal Feline, a special cat that seems to be strongly connected with the "dandy" characters in the Multiverse, being at times the pet of Jhary-a-Conel, Philander Groot, Jaspar Colinadus, Jephraim Tallow, and Jerry Cornelius. It is also later the pet of Yarmila, which may give a clue as to her future as a dandy.
On several occasions, Whiskers acted as the vessel for another's soul, including former emperor of Melniboné, Sadric (Elric's father), the sorcerer Drinij Bara, and even Jerry Cornelius.
Further, Whiskers can act as a conduit into another person's mind, as was done by Jhary to Amergin the Archdruid in The Oak and the Ram.