Upvote:-2
This is going to be brief, you can use links to read more.
First, about hereditary titles in a feudal system:
Second, not likely to be Chancellor, because it comes from Latin cancellarii, which signified court secretaries during Roman period. Later, during medieval European period (and even China's Tang dynasy), the Chancellor and similiar titles were essentially high-ranking government servants (something along the lines of "Chief Secretary" or "Head of Department").
This is convention, not strictly enforced, and much depends on which period and location. For instance, in modern British politics, the term "the Chancellor" usually refers to the Chancellor of the Exchequer (Minister of Finance), and Lord Chancellor is Lord High Chancellor of Great Britain (Minister in charge of the courts).
Finally, I believe the title is Viceroy, as in Viceroy of India. This usually requires, in British political convention, an Act of Parliament (law made by legislators) before the title can be conferred (i.e. non-hereditary, therefore cannot be asserted unless provisioned by Parliament).
However this is not a title for medieval period because, during that time, any town/city would be under the control/command of the nobility (see point 1, on hereditary titles). And at most, the "mayor" of the town would be serving a Duke, not the King.
NOTE: Pls see comment by TheHonRose below. The concept of titles and responsibilities, with attendant accountability, can get tricky really quick (and end up with legalese). I was/am trying to avoid this. Hence, my answer above is clearly not true for entire period and location. (I was trying to avoid an overly specific answer given the broadly worded question.)
Upvote:8
Chartered cities and towns, with their own self-government, were quite rare until late in the Medieval period. Notable exceptions were:
In the territory of much of modern Germany, as well as the Low Countries, the original stem duchies of the Holy Roman Empire rapidly splintered into a myriad of smaller sovereign states, most comparable in size to city states. For example the city of Liège in modern Belgium was a prince-bishopric from 985 C.E. administered by an appointed Bishop (who also administered the separate and larger Diocese of Liège).
In pre-Norman England towns and cities (other than London) were administered by a Reeve, the town-reeve, variously appointed by the Earl of the Shire or elected according to local custom. The main function of these early reeves was to implement the decisions of the court for each tithing, hundred, town and shire (the shire-reeve or sheriff).
In Spain the chief magistrate and administrator for cities and town was an Alcalde
Note that the powers, responsibilities and authorities of these officials would vary, often considerably, from city to city, though there would usually be commonality between cities and towns within a single sovereignty.
If you are wondering about the proper form of address for a mayor, a wide variation might be expected by country and era. Traditional English practice has been: