Itchy (I know the name is stupid.  You're not the only one who disagrees with the choice of names) is the father of Chewbacca, and grandfather of Lumpy (another stupid name).  He looks like a cranky old gray Wookiee, but actually he is pretty friendly.  He does have a strange fantasy (see Diahan Carroll), and he seems to be the one that is worried about Chewie the least.  He doesn't do much during the show, but is still the one you would remember most of seeing the show (probably because of the color of his fur, and the humorous shape of his mouth).