The Mirror of Morganna is an ancient mirror used to house an evil witch named Morganna. Morganna used the mirror to absorb people and bring out their evil opposites, using them to form an army. With this army, she took over Earth and plunged it into a time of unspeakable evil, which we know as the Dark Ages. However Morgana was defeated by looking at her reflection, which imprisoned inside the mirror until she was accidentally released by Atomic Roger.
She attempted to conquer Earth again, but was defeated by Betty and re-imprisoned in the mirror once more.