Depending on what the company produces and which markets they cater to, regulatory and quality authorities can vary tremendously. It could be GMP, GDP, GCP and GLP standards in compliance with MHRA; regulations in the Pharmaceutical and Biotechnology industries; or ISO 13485 for Medical Devices. Again, the quality assurance procedures and regulations will vary based upon the products and markets the company is operating in - this is why companies need specialist and dedicated quality assurance teams.
With respect to medicinal products, it is the World Health Organisation (WHO) who are responsible for setting global standards in quality assurance.