Warning: contains spoilers for Captain America Annual #1!
As part of Marvel's Infinite Destinies event, Captain America has revealed that SHIELD keeps a list of the most dangerous Marvel villains, identifying six familiar faces who are considered the biggest dangers to life on Earth. Infinite Destinies is currently taking place across Marvel's annuals, as heroes such as Thor, Iron Man, Spider-Man, and Black Cat come into contact with the Infinity Stone-Bearers - individuals who have bonded with, and now command the powers of, Marvel's Infinity Stones.
Fans have already seen Iron Man face off against Quantum, the bearer of the Space Stone, in Iron Man Annual #1, and Captain America Annual #1 sees Steve Rogers try to bring in Overtime, aka Hector Bautista, the bearer of the Time Stone. Despite assistance from the Black Widow, Overtime escapes, and Captain America meets with Nick Fury to brief him on the potential new threat of the Stone-Bearers running amok. It turns out the Infinity Stones are one item on the Abaddon Index - a list compiled by the now-defunct SHIELD on extinction-level threats to the planet Earth - and fans get to see six other villains who made the cut as top-level threats to all life on the planet.
Appearing first on the index is Galactus, the cosmic Devourer of Worlds who originally tried to consume Earth but has since entered into a pact to leave it unharmed. Joining him is Shuma-Gorath, a Cthulhu-like entity from outside time and space who generally acts as an antagonist of Doctor Strange, and who fans suspect may be the villain of the MCU's upcoming Doctor Strange in the Multiverse of Madness. Annihilus also appears on the list. The ruler of the Negative Zone and wielder of the Cosmic Control Rod, Annihilus is an interdimensional warlord responsible for the unparalleled disaster known as the Annihilation Wave, and has even come close to transcending reality and becoming a godlike constant in Marvel's reality. Thanos and Mephisto have earned their places with long careers of evil. The Mad Titan famously once wiped out half of all life, and is currently attempting to destroy Earth in Marvel's Eternals series, while Mephisto has long been Marvel's devil stand-in, and Avengers recently revealed he's working in concert with the Mephistos of countless other realities. The final villain shown on-panel is Apocalypse, the mutant supremacist whose belief in "survival of the fittest" led to the Age of Apocalypse - one of Marvel's darkest possible futures.
Cleverly, writer Jed MacKay and artist Juan Ferreyra leave one panel obscured, allowing readers to assume the presence of whichever seventh (or eighth, depending on the debatable sentience of the Infinity Stones when apart from their new human hosts) major-league villain they feel is most conspicuously absent. The suggestion of fizzing energy and an angular face allow for Dormammu or Ultron to take this open top-spot, though the choice to depict Apocalypse over either of these iconic villains is surprising. Apocalypse recently reformed as a representative of the mutant nation of Krakoa, and is currently trapped in another dimension. That he's still seen as such a major threat could signify how little trust is being extended to mutantkind.
What's interesting is that the Abaddon Index doesn't seem to be calculated on just raw power; while major threats like Chthon and Amatsu-Mikaboshi assuredly pose a danger to all life on the planet, they haven't attacked nearly as many times as the villains on this list, making it a particularly satisfying ranking of the forces an organization like SHIELD would most need to watch out for.
Hopefully, the fascinating Abaddon Index will return (perhaps in the ongoing Nick Fury story that stretches across each entry in Infinite Destinies), revealing more Marvel villains further down the list. For now, Captain America more than has his hands full with the Infinity Stones, but fans can rest assured that every face on the Abaddon Index will be back to menace the planet sooner rather than later.