Cheezy the Wiz
Socialist In A Hurry
Erich von Manstein
I think it depends on your definition of "losing" a battle. Much of the second half of the war, Manstein was conducting (or at least trying to) an elastic defense, which involves by nature giving ground and withdrawing. The only real battle I can think of him losing outright was Kursk, even though his individual units performed better than expected. He was also not the supreme commander at Kursk, either.