In the United Kingdom, Ireland, and parts of the Commonwealth, consultant is the title of a senior hospital-based physician or surgeon who has completed all of their specialist training and been placed on the specialist register in their chosen speciality. Their role is entirely distinct from that of general practitioners, or GPs.

The primary objective of a consultant is to use expert knowledge and skill to diagnose and treat patients while retaining ultimate clinical responsibility for their care. A physician must be on the Specialist Register before they may be employed as a substantive consultant in the National Health Service (NHS). This usually entails holding a Certificate of Completion of Training (CCT) in any of the recognised specialities, but academics with substantial publications and international reputation may be exempted from this requirement, in the expectation that they will practice at a tertiary level. "Locum consultant" appointments of limited duration may be given to those with clinical experience, with or without higher qualifications.

In South East Asian countries, practitioners who have at least post graduation degree like Doctor of Medicine and more than 10 years of clinical experience in treating patients are labelled as consultant.