Philip Henry Kerr, 11th Marquess of Lothian (1882–1940) was a British politician and diplomat.

He served in the South African government from 1905–10 after which he returned to England to found and edit the Round Table. In 1916, he was appointed David Lloyd George's private secretary and was active in the Paris Peace Conference.

Lord Lothian was best known in the United States for having aided Washington Post owner Eugene Meyer scoop the world on reporting Britain's King Edward VIII's relationship with Wallis Simpson, eventually leading to Edward's abdication of the crown.

He briefly served as Chancellor of the Duchy of Lancaster in 1931 and later as British Ambassador to the United States of America from 1939 to 1940.

Lord Lothian bequeathed Blickling Hall to the National Trust.

His grandson is the Conservative politician Michael Ancram, who is now the 13th Marquess.

|- style="text-align: center;" | width="30%" |Preceded by:
Sir Ronald Lindsay | width="40%" style="text-align: center;" |British Ambassador to the United States
1939–1940 | width="30%" |Succeeded by:
The Viscount Halifax