A signatory is a person authorized to sign documents on behalf of the company or organization. As a signatory, the person represents the company in front of clients, employees, creditors, and other stakeholders. A signatory signs contracts, treaties, agreements, bank documents, and all such documents which are legally enforceable.
A company may authorize different department heads to act and sign on behalf of the company. For instance, the chief accountant can sign invoices, payment slips, vouchers, and other documents. The HR manager is usually entrusted to sign the employment contracts, salary slips, and the like. The various operation heads would likewise be the signatories for job orders, purchase orders, quotations, etc.
A signatory is the legal face of the company representing all the documents to which he/she has put his signature.