Viper and the Serpent Society have obtained the Serpent Crown and have used it to release the snake demon, Set. The Avengers are fighting the Society and the Serpent, though the invincible deity quickly turns on Viper, knocking the Crown from her head. Captain America defends Viper from Set's attack, and takes a moment to implore her to reconsider her plans. Viper refuses to apologize, claiming she only does what she must to set the world right against the "heroes" that ruined it for her. She does relent, however, to offering a solution to re-imprisoning Set with the Serpent Crown, but before either she or Captain America can reach it, Cobra dons it believing he can succeed in controlling the snake demon where Viper failed. Declaring himself King Cobra, his reign is cut short when Set starts to devour him. When Captain America puts on the Crown next, surprisingly, he succeeds in sealing Set away with an intense stare-down. Later, as Viper and the Serpent Society are taken back to prison, Captain America admits to Iron Man that he wasn't sure he could beat Set, but he had to try to show Viper that setting the world right is what heroes do.
things I think about, like how in the comics The Serpent Crown is an important magical artifact that Namor is linked to & how in the movie he wears the crown of the Feathered Serpent, but unlike the comics where the crown is evil, the Feathered Serpent is a revered deity
Iirc there are 4 (remaining?) elder gods in 616, spawned from the demiurge (probably most closely tied to Billy). Of marvel’s heroes, there are a few with prominent connections to them: Wanda (chthon), Storm (oshtur), and Thor (gaea, though I started thinking about this when she appeared to nature girl a while back). Are there any characters you can think of that are connected to Set in a thematically similar way? It would be really interesting if someone explored these connections as you suggested
Gaea, Oshtur, Set, and Chthon are the most prominent of the surviving Elder Gods, but they're not the only ones. The current Immortal Thor series has established that the Utgard-Loki and Utgard-Thor are, in fact, part of the original pantheon of Elder Gods of Earth, who were sealed in Utgard by their sister, Gaea. The Utgard-Thor's true name is Toranos, but the Utgard-Loki's true name has yet to be revealed. In the past, Utgard's residents, Those Who Sit Above In Shadow, have been referred as the Elder Gods of Agard. I'm curious if that will retconned, or if this new backstory only applies to Toranos and his brother.
Anyways, to answer your actual question, Set doesn't really get as much as page time as his siblings, and his influence tends to be felt in more subtle ways-- relatively speaking, of course. There aren't any A-list characters with direct connections to him, especially not heroes. Set is heavily involved in the history of Atlantis and Lemuria-- in particular, the Lemurian royal family carries his bloodline. Llyra, who is a recurring Namor villain, is a priestess of Set who frequently appears as the bearer of the Serpent Crown.
She's probably the most closely connected character to Set, but she only has 43 appearances and hasn't been in any comics since 2007. So, in terms of representation, you can tell Set really gets the short end of the stick
Another interesting villain is the sorcerer Damballah*, who was an early enemy of Doctor Voodoo. He's a human devotee of Set with no connection to Lemuria. It would be cool for him to come back, but it should come as no suprise that the character is... kinda racist and might be difficult to update for modern comics.
There are multiple characters and entities named Damballah in the Marvel universe. Damballah, or Damballa, is the name of a deity or spirit in African diaspora religions. Like most polytheistic gods, this deity does exist in the Marvel universe as a living being, and appears alongside other African and African-diaspora religious figures in the gods realms Olun and Bondye. He primarily goes by the name Dam-Ayido Wede.
Damballah is also the name of an Elderspawn demon, who is in fact the child of Set.
The sorcerer Damballah's real name is Josué Koulèv, and he was a devotee of Set who received powers from the Elder God through a magical amulet. He used the name Damballah to pose as a the loa and gather a cult following.
Also, in case you're wondering, Set and the Egyptian god Seth are distinctly separate entities in the Marvel world, unlike Gaea, who is the same as the Greek goddess.
A three page ad (above) for the Atlantis Attacks crossover event that ran in the Marvel Annuals in 1989. Another ad (below) that ran in some titles with a June 1989 cover date.