Quote Originally Posted by Marshal Murat
Ancient Bracket
Alexander the Great
Hannibal Barca
Julius Caesar
Sulla
Gaius Marius
Mithridates the Great
Antiochus III
Scipio Africanus
Cyrus the Great
Rather than Sulla or Marius, solidly competent but not exemplary, I'd say you'd be better off with Pyrhus, Aetius, and/or Belisarius. Qin Shi Huang, Sun Bin, Sun Wu (aka, Sun Tzu), Chandragupta Maurya, and/or Ashoka would break up the Mediterranean monopoly of the current list. In particular, Qin Shi Huang and Chandragupta Maurya, as actual empire builders, should be on the list ahead of talented wannabes like Mithradates.

Renaissance Bracket
Gustavus Adolphus
Tilly
Wallenstein
Jan Sobieski
Stanislaw Zolkiewski
Chodkiewicz
Oda Nobunaga
Totoyomi Hideyoshi
Tokugawa Ieaysu
Oliver Cromwell
Maurice of Nassau
Not sure if they belong here or in a Middle Ages bracket, but the Aztec emperors Itzcoatl, Moctezuma I, and Ahuitzotl deserve consideration, as does Pachacuti Inca Yupanqui of the Inca.

Napoleonic Bracket
Napoleon Bonaparte
'Stonewall' Jackson
Robert E. Lee
Wellington
Frederick the Great
Maurice de Saxe
Duke of Marlborough
Prince Eugene
George Washington
Benedict Arnold
I think Louis Davout and/or Simon Bolivar are more deserving of a spot than Benedict Arnold, competent yet essentially insignificant.

Modern Warfare Bracket
Guderian
Manstein
Zhukov
Rommel
Patton
Montgomery
Slim
MacArthur
Hindenburg
Ludendorff
von Runstedt (OK, enough of the Wehrmacht) and Koniev easily more deserving than Hindenburg who, with Ludendorff on the list, is redundant (and both Hindenburg and Ludendorff should perhaps make way for Max Hoffmann). For more modern representation, you should consider Vo Nguyen Giap.

Naval Warfare Bracket
Nelson
Nimitz
Sun-Yi
Jellicoe
Beatty
Scheer
de Ruyter and Togo are musts here. Also, it should be Yi Sun-shin; Sun-Yi is Woody Allen's wife.