Raymond George Hardenbergh Seitz (born December 8, 1940) is a former career diplomat and U.S. Ambassador to the United Kingdom. He was born in Honolulu, Hawaii on December 8, 1940. He is the son of United States Army Major General John F. R. Seitz (d. 1978) and Helen (Hardenbergh) Seitz (d. 1953).
He graduated from Yale University in 1963 with a BA in history, following which he spent two years teaching in Dallas, Texas. He joined the US Foreign Service in 1966. He was the first career diplomat in modern history to be made Ambassador to the UK – the post is usually given to a political appointee.
Seitz was a member of the Founding Council of the Rothermere American Institute at Oxford University.
Since retiring from the foreign service, Seitz has held numerous directorships, governorships, and trusteeships. He was Senior Managing Director at Lehman Brothers International from 1995–1996, and Vice-Chairman from 1996–2003. He has held non-executive directorships on the boards of British Airways, Hong Kong Telecom, Marconi, General Electric Co, Rio Tinto Group and Cable & Wireless. As of November 2004, he is currently on the boards of the Chubb Group, PCCW, and Hollinger International.