castellan
noun
cas·tel·lan ˈka-stə-lən 
: a governor or warden of a castle or fort
Example Sentences
Recent Examples on the Web Conversely, the castellan (the commander of the castle and the king's loyal man) might capitulate if certain promises of safety, payment, and bounty were provided. 
William Gurstelle, Popular Mechanics, 11 Apr. 2019
William Gurstelle, Popular Mechanics, 11 Apr. 2019 Word History
Etymology
Middle English castelleyn, from Anglo-French castelain, chastelein, from Latin castellanus occupant of a fortress, from castellanus of a fortress, from castellum fortress — more at castle
First Known Use
14th century, in the meaning defined above