When a person has been declared incompetent and the court appoints someone to handle their financial and physical affairs, what is that person called?
The legal term for the person placed in charge of an individual's care or their property is "guardian." The individual being cared for is a "ward." When the court appoints someone for this duty, the term is "guardian ad litem."
Here is a link to our encyclopedia for more information about guardians and wards.