An officer of the court of chancery (or equity). He is an assistant to the chancellor (or judge); usually there are 12 masters in chancery for a chancellor. They are in charge of doing the gruntwork that arises from cases brought to court. Each master has control over a number of lesser clerks of the court, who help him with his tasks.
In England there are two types of masters in chancery; masters in ordinary, who execute the orders of the court, and masters extraordinary, who take affidavits on matters of the court and keep track of courtroom events.
Besides this, masters in chancery may be assigned other duties by their local courts as needed.