The term 'Access Controller' refers to a person or system responsible for controlling access to a certain area or resource. The two words that can be used to describe this role are 'SENTRY' (6 letters) and 'GATEKEEPER' (10 letters). A SENTRY is someone who stands guard and watches over a certain area, while a GATEKEEPER is someone who controls access to a certain area or resource. Both roles involve monitoring and controlling access to a certain area or resource, making sure that only authorized personnel are allowed in.