In order to answer your question, you need to identify the play to which you are referring. A critical analysis of the characters would involve a careful study of their nature. Ask yourself these questions: How would I describe this character to another person if they were real? Start with physical appearance and consider the things they say, do, believe and what others say about them. Does the character's physical appearance relate in any way to their attitude or is it contrary? Make a value statement: is the character good or evil? Are they morally ambiguous?
Hope this helps.