This is an interesting question and certainly a very subjective one. Hamlet would be something quiet and pensive, like perhaps a golden retriever because he's also very loyal. He's not without ability and power, but unless he receives a direct command, he's not quick to action. The ghost of King Hamlet would be more like an owl: large, unapproachable, a little bit scary, and a little bit mysterious, but with a air of wisdom. King Claudius would have to be an animal that is associated with the negative, like a rat. He killed his own brother in order to get the crown and more. Gertrude I see as a sheep - she just follows along. She followed Claudius, she followed Hamlet. Ophelia would likely be an animal that is associated with softness, a sweetness, and definitely not a swimmer - perhaps a dove. Polonius is a weasel. He is sneaky and he manuevers around in a way that makes him seem somewhat lithe. Laertes would be a dog, too, like Hamlet. He'd be a pitbull: fierce, quick-tempered, and somewhat tenacious.
Thanks thats kinda what i was thinking too