My 2 quatloos on great generals:

The Ancients
Genghis Khan
Alexander the Great
Scipio Africanus
Fabius Maximus
Cyrus the Great
Hannibal

Belisaurius
Khalid ibn al-Walid
Tamerlane
Saladin

Middle Ages through the 19th Century
Gustavus Adolphus
John Sobieski
Scharnhorst
Clausewitz
Charles Martel
Moltke the Elder
Duke of Wellington
Napoleon

20th Century
Montgomery
Marshall
Patton
Zhukov
Von Seeckt
Chuikov
Eisenhower
Von Manstein
Balck
Puller

Admirality
Jacky Fisher
Ernest King
Nimitz
Nelson
Decatur
Rickover - for his scientific work
Mahan

Air Marshals and the like
Billy Mitchell
Doolittle
Wolfram von Richtofen
Kesselring - was also an Army officer
LeMay - a savage, but since he as on our side it's ok
Hans Ulrich Rudel (although he may not have been a General - don't know)
Bomber Harris
Douhet - he's been too influential, and that's why he's on the list