A bailiff is a governor

Governor

A governor is a governing official, usually the executive of a non-sovereign level of government, ranking under the head of state...

 or custodian (cf. bail

Bail

Traditionally, bail is some form of property deposited or pledged to a court to persuade it to release a suspect from jail, on the understanding that the suspect will return for trial or forfeit the bail...

); a legal officer to whom some degree of authority, care or jurisdiction is committed. Bailiffs are of various kinds and their offices and duties vary greatly.
The term was first applied in England

England

England is a country that is part of the United Kingdom. It shares land borders with Scotland to the north and Wales to the west; the Irish Sea is to the north west, the Celtic Sea to the south west, with the North Sea to the east and the English Channel to the south separating it from continental...

 to the king's officers generally, such as sheriff

Sheriff

A sheriff is in principle a legal official with responsibility for a county. In practice, the specific combination of legal, political, and ceremonial duties of a sheriff varies greatly from country to country....

s, mayor

Mayor

In many countries, a Mayor is the highest ranking officer in the municipal government of a town or a large urban city....

s, etc., and more particularly to the chief officer of a hundred. The county

Historic counties of England

The historic counties of England are subdivisions of England established for administration by the Normans and in most cases based on earlier Anglo-Saxon kingdoms and shires...

 within which the sheriff exercises his jurisdiction is still called his bailiwick

Bailiwick

A bailiwick is usually the area of jurisdiction of a bailiff, and may also apply to a territory in which the sheriff's functions were exercised by a privately appointed bailiff under a royal or imperial writ. The word is now more generally used in a metaphorical sense, to indicate a sphere of...

, while the term bailiff is retained as a title by the chief magistrates of various towns and the keepers of royal castles, such as the High Bailiff of Westminster

Palace of Westminster

The Palace of Westminster, also known as the Houses of Parliament or Westminster Palace, is the meeting place of the two houses of the Parliament of the United Kingdom—the House of Lords and the House of Commons...

, the Bailiff of Dover Castle

Dover Castle

Dover Castle is a medieval castle in the town of the same name in the English county of Kent. It was founded in the 12th century and has been described as the "Key to England" due to its defensive significance throughout history...

, etc.