A chamberlain is a high-ranking official who manages the household of a king, queen, or noble family. In medieval castles and palaces, the chamberlain controlled access to the ruler's private chambers, organized ceremonies, supervised servants, and handled the finances of the royal household.

Think of a chamberlain as a combination of chief of staff, head butler, and financial manager all rolled into one trusted position. The chamberlain decided who could meet with the king, made sure the castle ran smoothly, and kept track of the royal treasury. Because chamberlains spent so much time close to powerful rulers, they often became powerful themselves, sometimes advising on important decisions.

Today, some places still have officials called chamberlains. The British royal family has a Lord Chamberlain who organizes major events like coronations. Some cities have a City Chamberlain who handles ceremonial duties or financial matters.

The word can also mean a treasurer or financial officer in city government: someone who manages public money and keeps careful records of how it's spent.