As a subject matter expert in comic book lore and the Marvel Universe, I can provide an informed perspective on the character of the Hulk. The Hulk, a creation of Stan Lee and Jack Kirby, is a character with extraordinary abilities and resilience. However, the concept of immortality is complex and can be interpreted in different ways.

In the comic books, the Hulk has been portrayed as having a highly regenerative healing factor, which allows him to recover from virtually any injury, including those that would be fatal to a normal human. This has led some to describe the Hulk as being effectively immortal in terms of his ability to heal and survive.

However, the Hulk is not truly immortal in the sense that he cannot die. He is still vulnerable to certain threats and circumstances that could result in his death. For example, he could potentially be killed by powerful enough forces, such as cosmic beings or highly advanced technology. Additionally, the Hulk's mortality is tied to Bruce Banner's, as the Hulk is a manifestation of Banner's subconscious and is affected by Banner's physical condition.

In summary, while the Hulk possesses an incredible healing ability that makes him extremely long-lived and resistant to aging and disease, he is not immortal in the strictest sense of the word.

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The Hulk knows that if Banner dies, he dies as well. So whenever Banner is near death, the Hulk takes over and heals their body with his regenerative powers. Essentially keeping Banner as immortal as he is. I don't believe it's canon but it might shed light on how Banner might become immortal due to the Hulk's powers.read more >>