Cognomen Сэр (Sir 
, Сэр 
) , globally, is a common family name. The family name Сэр is characteristic of Bhutan, where it is quite a common surname, Maldives, and Taiwan, where it is quite a rare surname. In absolute terms, it is the most numerous in Bangladesh, China, and Nepal. Very seldom, Сэр is the forename as well as the last name.