Lothar the Barbarian
During the EEnE special, Ed Edd n Eddy's Bo Haw Haw, Ed dressed as Lothar. As Lothar, Ed becomes unafraid of anything (Even Sarah), and uses a spatual as his weapon. He calls it his flipper.
During "The Day the Ed Stood Still" Ed dressed as Edzilla, a evil monster. While Edzilla, Ed became stronger, faster, and more durable. He lost this form when Sarah took off his mask.
Wing Ed is the combination of Ed and Ingram. He is strong, fast, and vulnerble to metal. He can fly with his wings.
In certain fan games, Ed gains the transformation called Super Ed. He becomes much stronger, and can fly. Plus, he is invincible. He achives this along with Eddy and Double-D.
Dark Ed is the combination of Ed, and Evil Tim. Not much is known about this form, exept that he becomes more powerful, and much faster.