Appearing in "The Day of the Defenders!"
- Defenders (First appearance)
- Hoggoth (Invoked)
- Vishanti (Invoked)
- Oshtur (Invoked)
- Silver Surfer (Norrin Radd) (Cameo)
- Valtorr (Invoked)
- Ezra (First appearance)
- Sarey (First appearance)
- Denak (Invoked)
- Satannish (Invoked)
- Llyra (Illusion)
- Avengers (Mentioned)
Races and Species:
- Cloak of Levitation
- Eye of Agamotto
- Power Cosmic (Cameo)
- Silver Surfer's Surfboard (Cameo)
Synopsis for "The Day of the Defenders!"
After being called to his old foe Yandroth on his deathbed, Doctor Strange is warned by the techno-wizard that he has created a doomsday machine called the Omegatron to destroy the Earth five hours after it's activated.
In order to save the world, Dr. Strange gathers the aid of Namor the Sub-Mariner. He recommends getting the Silver Surfer to help, but they find that he is busy trying to break through the barrier that keeps him on Earth. They witness the Surfer hitting the barrier and falling back to Earth unconscious and determine that they cannot wait for him to recover.
They instead seek the assistance of the Hulk to find the Omegatron and destroy it, before it can start a nuclear chain reaction that will destroy the planet. They pin point the device to a lighthouse in Maine. The three heroes enter the lighthouse from different paths using their special skills. Namor enters through beneath through the ocean. The Hulk enters through the front, while Dr. Strange uses his astral form to scout the building. Strange eventually enters the main room where he meets Omegatron, who explains that Yandroth sent Strange on this path intentionally so that Omegatron could harness the power from Strange's allies. Namor and Hulk soon enter and Strange tries to explain why they cannot harm the machine or else the planet will be destroyed. The two take this as a hallucination presented to them by Omegatron and attempt to force their way past. Strange, left with no other option, pits his friends against each other to distract them, making them see hallucinations to fight one another.
With ample time, Strange then casts a spell around the lighthouse slowing down the progression of time to an eternal crawl, so that it will be centuries before the Omegatron finally counts down it's final moments before detonation. With the threat of the Omegatron at least postponed indefinitely, Strange explains what happened to the now somber group. Dr. Strange declares that should they need to reunite, they will be called the Defenders. However, Hulk expresses his distaste for the idea of being in a group after having already been in the Avengers.
Appearing in "The Sub-Mariner and the Icebergs"
Synopsis for "The Sub-Mariner and the Icebergs"
With reports that ships from the surface world are sailing close to Atlantis, Namor goes to the Emperor and tries to convince him to allow a full scale assault. However, the Emperor refuses to act rashly suggesting to Namor that they stop and see what the surface dwellers want before they attack. Unwilling to be patient, Namor convinces Namora and a number of Atlantean warriors to help him use Aero-Subs to push icebergs around the ships trapping them. Fearing that they will be trapped in the ice, the captain of the ship orders the icebergs blasted and the resulting blasts rock Atlantis with damage. Namor then returns to the Emperor and tells him what happened, and the furious Emperor decides to attack. However, he decides to engage in sabotage instead and sends Namora up to the ships to wreck them. However, Namora is easily captured by the crew and they send a message down to the Sub-Mariner asking him to talk with them and exchange a release of Namora.
Namor agrees to meet with the captain and learns that he and his crew are only searching for Uranium and seek safe passage through the Sub-Mariner's domain. Namor agrees to allow them safe passage and they release Namora. However, Byrrah is not convinced by this show of peace and decides to take matters into his own hands by trying to plant a bomb on the bottom of the the ships. However he is spotted by the Sub-Mariner who quickly stops Byrrah from destroying the ships. Shortly afterward the captain drops down another message warning Namor of an impending undersea earthquake that will rock Atlantis.
Namor is able to warn the Emperor and evacuate the kingdom in time to avoid a massive slaughter when the earthquake hits. The Sub-Mariner then points out that without the warning from the surface dwellers they would have all died, quelling even Byrrah's doubts about the surface people. With their lives intact, Namor leads his people back into the ruins of Atlantis so that they can rebuild.
Appearing in "The Return!"
- Munnopor (Invoked)
Races and Species:
Synopsis for "The Return!"
This story takes place prior to the formation of the Defenders.
Dr. Strange returns home to his Sanctum Sanctorum after a long absence. There he finds that Wong is still looking after somebody who claims to be Dr. Strange. However, during the battle the powerless Strange is easily defeated and knocked out by his impostor.
While unconscious, Strange is visited by his master the Ancient One who restores Strange's mystical powers and his original identity.
Strange then attacks his impostor once more but this time easily defeats the foe. Unmasking him, Strange finds that his doppelganger is none other than his mortal enemy Baron Mordo.
Realizing that he cannot leave his place unattended nor shirk his responsibilities, Strange resumes his position of master of the mystic arts.
Who are - The Defenders? None other than Dr. Strange - the Sub-Mariner - and the Hulk! No wonder we made this one king-size!
- This issue sees the return of Dr. Strange since his series was canceled  and since his absence. Right away they decide to dispose of the "mask" that Strange was wearing close to the end of his series and change his last name from Stephen Sanders back to Stephen Strange.
- While this issue had a December 1971 cover date, because it was published quarterly it came out the same time as issues with a September or October 1971 cover date.
- This issue was reprinted in July 2019 as Marvel Feature #1 Facsimile Edition. It includes the original: ads, "Stan's Soapbox," and "Mighty Marvel Checklist."