ウィリアム・ロジャー・ルイス（William Roger Louis、1936年5月8日 - ）は、アメリカ合衆国の歴史学者。専門は、イギリス帝国史。

ミシガン州デトロイト生まれ。オクラホマ大学卒業。オックスフォード大学セントアントニー校留学を経て、ハーバード大学で博士号取得。エール大学を経て、1970年からテキサス大学オースティン校歴史学部で教鞭をとっている。1993年、イギリス学士院に選出される。1999年、大英帝国勲章を授かる。

著書
Ruanda-Urundi, 1884-1919, Clarendon Press, 1963.
Great Britain and Germany's lost colonies, 1914-1919, Clarendon Press, 1967.
British strategy in the Far East, 1919-1939, Clarendon Press, 1971.
Imperialism at bay 1941-1945: the United States and the decolonization of the British Empire, Clarendon Press, 1977.
The British Empire in the Middle East, 1945-1951: Arab nationalism, the United States, and postwar imperialism, Clarendon Press, 1984,
In the name of God, go!: Leo Amery and the British Empire in the age of Churchill, W. W. Norton, 1992.
Ends of British imperialism: the scramble for Empire, Suez and decolonization: collected essays, I. B. Tauris, 2006.

編著
Britain and Germany in Africa: imperial rivalry and colonial rule, edited by Prosser Gifford and Wm. Roger Louis, Yale University Press, 1967.
E. D. Morel's history of the Congo reform movement, edited by Wm. Roger Louis and Jean Stengers, Clarendon Press, 1968.
France and Britain in Africa: imperial rivalry and colonial rule, edited by Prosser Gifford and Wm. Roger Louis, Yale University Press, 1971.
National security and international trusteeship in the Pacific, edited by Wm. Roger Louis, Naval Institute Press, 1972.
The origins of the Second World War, edited by Wm. Roger Louis, Wiley, 1972.
Imperialism: the Robinson and Gallagher controversy, edited by Wm. Roger Louis, New Viewpoints, 1976. 
Australia, New Zealand, and the Pacific Islands since the First World War, edited by William S. Livingston and Wm. Roger Louis, University of Texas Press, 1979.
The Transfer of power in Africa: decolonization, 1940-1960, edited b y Prosser Gifford and Wm. Roger Louis, Yale University Press, 1982.
The "Special relationship": Anglo-American relations since 1945, edited by Wm. Roger Louis and Hedley Bull, Clarendon Press, 1986.
The End of the Palestine mandate, edited by Wm. Roger Louis and Robert W. Stookey, University of Texas Press, 1986.
Decolonization and African independence: the transfers of power, 1960-1980, edited by Prosser Gifford and Wm. Roger Louis, Yale University Press, 1988.
Musaddiq, Iranian nationalism and oil, edited by James A. Bill and Wm. Roger Louis, Tauris, 1988.
Suez 1956: the crisis and its consequences, edited by Wm. Roger Louis and Roger Owen, Clarendon Press, 1989.
The Iraqi revolution of 1958: the old social classes revisited, edit ed by Robert A. Fernea and Wm. Roger Louis, Tauris, 1991.
Churchill, edited by Robert Blake and Wm. Roger Louis, Oxford University Press, 1993.
Adventures with Britannia: personalities, politics and culture in Britain, edited by Wm. Roger Louis, I. B. Tauris, 1995.
The Oxford history of the twentieth century, edited by Michael Howard and Wm. Roger Louis, Oxford University Press, 1998.
More adventures with Britannia: personalities, politics and culture in Britain, edited by Wm. Roger Louis, University of Texas Press, 1998.
The Oxford history of the British Empire, vol. 4: The twentieth century, edited by Judith M. Brown and Wm. Roger Louis, Oxford University Press, 1999.
A revolutionary year: the Middle East in 1958, edited by Wm. Roger Louis and Roger Owen, I. B. Tauris, 2002.
Still more adventures with Britannia: personalities, politics and culture in Britain, edited by Wm. Roger Louis, I. B. Tauris, 2003.
Burnt orange Britannia, edited by Wm. Roger Louis. I .B. Tauris, 2005.
Yet more adventures with Britannia: personalities, politics and culture in Britain, edited by Wm. Roger Louis, I.B. Tauris, 2005.