A dupe or tool for another, a sucker, as in You always try to make a cat's paw of me, but I refuse to do any more of your work. This term alludes to a very old tale about a monkey that persuades a cat to pull chestnuts out of the fire so as to avoid burning its own paws. The story dates from the 16th century and versions of it (some with a dog) exist in many languages.
Heh. Our own Montana Cat's Paw