While trying to defend Earth from the extra-dimensional, demonic beings called the Undying Ones, Sorcerer Supreme Dr. Strange manipulated Prince Namorinto aiding him, and then teamed with the monstrous Hulk to ward off the demons.

Later, when the Yannian scientist Yandroth menaced Earth with the Omegatron doomsday device, Dr. Strange persuaded a reluctant Hulk and Namor to help him thwart Yandroth's scheme, forming the "non-team" known as the Defenders. After Yandroth's defeat, Hulk and Namor vowed never to work together again, but Strange managed to hold their informal alliance together over time. Unlike other super-teams, these Defenders had no charter or by-laws, no permanent headquarters, no fixed roster, and little affection for each other.