The entity that determines the purposes and means of personal data processing (GDPR Art. 4(7)).
A data controller is the natural or legal person, public authority, agency, or other body that, alone or jointly with others, determines the purposes and means of the processing of personal data.
Run a free ComplianceIQ audit against GDPR and we'll surface every gap on this — and the other controls auditors flag — with the exact clause references to fix.