Philip Duncan Greenish (born 5 September 1951) was a Rear Admiral in the UK Navy. On retirement from the navy in 2003 he assumed the role of the Chief Executive of the Royal Academy of Engineering.
Greenish read Engineering Science at Durham University, graduating in 1972. He is a graduate of the Royal College of Defence Studies. His early naval career was spent as an engineer in frigates and destroyers and in shore appointments in engineering training, front-line support and naval plans. He served for two years with the Canadian Navy in Halifax Nova Scotia.
Senior Navy appointments included: as a Rear Admiral, responsibility for engineering, personnel and logistic support for the front line of the Royal Navy and Royal Marines, including leadership of a major reorganisation of the Fleet Headquarters; Director of Operational Requirements for sea systems; two years as military assistant to the MOD’s Chief of Defence Procurement; and responsibility for the conduct of naval weapon trials and acceptance.
- Council Member of the Science and Technology Facilities Council
- Trustee of the Daphne Jackson Trust 
- Member of the WISE Board (Women into Science and Engineering)
- Trustee of the Science Media Centre.
On climate change: "The time has come for engineers to demonstrate that it's through engineering that issues like climate change will be addressed."