An inventor is the natural person who has made the original inventive contribution embodied in an invention, typically reflected in a patent application or granted patent. In UK law (England & Wales, Scotland and Northern Ireland), the concept is principally defined in the Patents Act 1977, which treats the inventor as the “actual deviser” of the invention. Irish law adopts a broadly similar approach under the Patents Act 1992, focussing on the person who created the invention.In all these jurisdictions, only individuals (not companies) can be inventors, although employers and others may acquire ownership (patent entitlement) by statute, contract or assignment. Joint inventors arise where more than one person contributes materially to the inventive concept.Correct identification and naming of the inventor in patent applications is legally and commercially significant, affecting entitlement disputes, employee compensation claims, validity challenges and enforceability of patent rights. Misidentification can lead to rectification proceedings or, in some circumstances, revocation.Across the UK and Ireland, the term “inventor” is used consistently in patent law, patent litigation, technology transfer, R&D agreements and employee invention policies, and is central when advising on ownership, exploitation and infringement of patent-protected technology.