Venom and the Hulk share a surprising power highlighted in each of their newest comic series: immortality. Other than brute strength and the additional personalities woven into each of their psyches, the similar ability between Hulk and Venom makes the two extremely hard to kill. As shown in the Immortal Hulk saga and more recently in the King In Black crossover Venom books, both Eddie Brock and Bruce Banner have the power of immortality.
The Hulk has been canonically immortal since the first issue of Immortal Hulk by Al Ewing with art by Joe Bennett, hence the title, but Venom only recently joined the ranks of the unkillable. In King In Black #2 by Donny Cates with art by Ryan Stegman, Knull kills Eddie Brock by stripping him of his symbiote and throwing him off a building. It wasn’t until Venom #32 by Donny Cates with art by Iban Coello that fans realized Brock wasn’t dead after all but lived on through the hive mind of Knull because of his prior connection with Venom. Eddie was able to stay alive as a codex due to the bond he and his symbiote shared, proving that he achieved immortality granted to him by the img of his superhuman abilities, exactly like the Hulk.
Where the two morally grey heroes differ however is in the extent of their immortality and the location of their respective afterlives. Upon his death, the Hulk is taken to the Below-Place through the ever eerie Green Door. The img of the Hulk’s immortality is stemmed from his exposure to gamma radiation which allows the strongest Avenger to come back to life fairly quickly after being killed. The details of Eddie Brock’s eternal life are currently being explored through upcoming Venom and King In Black titles, but what fans know so far is that his afterlife exists within Knull’s hive mind and Brock will need to re-bond with Venom to be brought back into the physical world.
While Venom’s immortality has been confirmed in the comics, though Hulk’s has been more fully explored and seemingly more reliable, there is one discrepancy in the logic behind Brock’s eternal life. Since Eddie’s permanence is a new development within the comic books, fans are currently unsure whether or not his immortality stems from his symbiosis with Venom or if it is entirely dependent on the god-king Knull himself. After all, Brock is only still alive through a piece of his remaining self embedded within Venom whose entire afterlife is a collection of minds within the Lord of the Abyss’ metaphorical hive.
Perhaps Knull is ironically the only reason for Eddie Brock’s everlasting life after the cosmic entity killed the symbiote host himself. While the root of Venom’s deathlessness will likely remain a mystery until the final pages of the last King In Black installment, at this time both Venom and the Hulk share the power of immortality.