From Longman Business Dictionary
registrarre·gis·trar /ˌredʒəˈstrɑː◂ˈredʒəstrɑːr/ noun [countableC]JOBFINANCE the person whose duty is to record changes in the people who own the shares of a company. The registrar is usually someone who works for the companyThe Companies Act provides for registrars to give complete shareholder lists to persons on payment of a fee.