C3PO can function like the Fool, but I find that he's not a great example of it because he's used for comic relief but doesn't really pursue any of the other Fool elements, like wanting pleasure or using superior intellect.

Jabba, on the other hand, reflects the wannabe cunning and decadence of the Fool consumed by Shadow, and is a fairly major villain in the series, though he spends a lot of time out of the limelight.