Historically speaking, Namor, the Sub-Mariner hasn't typically been on the best of terms with the Avengers. The Avenging Son's arrogance and fiery temper often keeps him alternating between hero and villain, occasionally placing him at odds with Earth's Mightiest Heroes. Still, after decades of moral ambiguity, Namor was eventually given the chance to join the Avengers.

Namor first encountered Earth's Mightiest Heroes back in 1963's Avengers #3, by Stan Lee, Jack Kirby, Paul Reinman, Stan Goldberg and Sam Rosen. In this issue, the Sub-Mariner approached the Hulk, right after the Green Goliath quit the Avengers. At the time, Namor was quite similar to the Hulk, waging war on the surface world with his tremendous strength.

Since they both hated humans, Namor and the Hulk decided to team up and destroy the Avengers. Attacking the Avengers in their first meeting, the Sub-Mariner certainly left a lasting impression on the team. In the next issue, Namor left an even bigger impact on the Avengers by unknowingly freeing Captain America from suspended animation, right before the team found him.

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Unfortunately, the Sub-Mariner followed up this good deed by attacking the Avengers again and trying to invade the surface world with his fellow Atlanteans. For years following these initial encounters, the Sub-Mariner was an on-again off-again enemy of the Avengers and most Marvel heroes, before they eventually came to a truce. Yet it wasn't until 1985's Avengers #262 (by Roger Stern, John Buscema, Tom Palmer, Christie Scheele and Jim Novak) that Namor actually became a card-carrying member of the team. At the time, Namor had been stripped of his title as Prince of Atlantis, losing his people's loyalty in the process.

The Avengers encountered Namor on an island called Hydrobase, which they were looking to use as a new base for their Quinjets. After a brief skirmish with Hercules, Namor was asked to be an Avenger by Captain America. This was a fairly big deal, since Steve Rogers knew Namor better than any of the other Avengers, after fighting alongside him during World War II.

Captain America thought being an Avenger would give Namor a sense of purpose in the same way it did for him when he first came out of suspended animation. Moreover, Steve revealed to Namor that it was he who had brought Captain America back from suspended animation, revealing their connection. With this knowledge, Namor accepted, finally becoming an Avenger.

As one of Earth's Mightiest Heroes, Namor fought foes such as Kang, the Lava Men, Blastaar and even the forces of Olympus. Namor was also one of the Avengers present during the "Secret Wars II" crossover, working with his teammates to neutralize the Beyonder.

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Namor fighting Hercules on the cover of 1985's Avengers #262

During his time on the Avengers, Namor clashed with several of his teammates. The Sub-Mariner also left the team several times. The first time, Namor left to search for his love, Marrina. As a result, Namor missed the classic "Under Siege" storyline, where the Masters of Evil took over Avengers Mansion. Later on, Namor returned, but he left once again in 1988's Avengers #293 (by Walt Simonson, John Buscema, Tom Palmer, Max Scheele and Bill Oakley) after Marrina's apparent death.

The Sub-Mariner returned to the team once more, in 1989's Avengers #305 (by John Byrne, Paul Ryan, Tom Palmer, Christie Scheele, Marc Siry and Bill Oakley). It was in 1989's Fantastic Four Annual #22 (by Roy Thomas, Rich Buckler, Tony Dezuniga, John A. Wilcox and Janice Chang) that Namor left the team for good.

In the aftermath of the "Atlantis Attacks" crossover, the Sub-Mariner left to be with his cousin, Namorita, deciding he should spend more time with family. Since then, Namor has returned to his uneasy relationship with the Avengers from before he joined the team. However, sometimes the Atlantean's old membership with Earth's Mightiest Heroes has come into play, allying the Sub-Mariner with his old teammates.

On other occasions, however, Namor has sided against his former allies. During "Avengers vs. X-Men," for example, the Sub-Mariner sided with the X-Men and became one of the Phoenix Five, hunting down the Avengers. Even though Namor still alternates between the role of hero and villain, the Sub-Mariner was a full-fledged hero during his time with Earth's Mightiest.

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