Appearing in "Earth X, Chapter 4"
- Inhuman Royal Family
- Doctor Doom (Reed Richards) (Impersonates Doctor Doom)
- Captain America (Steve Rogers)
- Black Panther (T'Challa) (Main story and flashback) (Origin revealed)
- Beast (Dr. Hank McCoy)
- Storm (Ororo Munroe)
- The Skull
- Skull's Army
- Redwing (Wyatt Wingfoot) (Joins team) (Controlled by The Skull)
- Domino (Neena Thurman) (Controlled by The Skull)
- Namor (Controlled by The Skull)
- Sandman (William Baker) (Controlled by The Skull)
- Texas Jack (Marshall Muldoon) (Controlled by The Skull)
- Spiders Man (Controlled by The Skull)
- Iron Maiden (Controlled by The Skull) (Main story and flashback) (Origin revealed)
- Sunspot (Bobby Da Costa) (Controlled by The Skull)
- The Wizard (Bentley Wittman) (Controlled by The Skull)
- Feral (Maria Callasantos) (Controlled by The Skull)
- Uatu (Voice)
- Panther Cult (First appearance) (Main story and flashback) (Origin revealed)
- Ulysses Klaw (First appearance) (Only in flashback)
- The Watcher (X-51)
- Ani-Men (First appearance)
- Ahura Boltagon (Mentioned)
- Professor X (Charles Xavier) (Mentioned) (Deceased)
- Spider-Man (Peter Parker) (Mentioned)
- The Skull's father (Mentioned)
- Moses (Mentioned)
- Jack Nicholson (Mentioned)
- The Joker (Jack Napier) (Mentioned)
- Iron Maiden (Mentioned)
- Bucky (James Barnes) (Illusion)
- U.S. Army (Illusion)
- Nazi Party (Mentioned)
- Adolf Hitler (Mentioned)
- Harpy (Betty Ross) (First appearance)
- Hulk & Bruce Banner
- Wong (First appearance)
- Clea Strange (First appearance)
- Tony Stark (Mentioned)
Races and Species:
- Watchers (Voice)
- Gods (Mentioned)
- Humans (Main story and flashback)
- Demons (Mentioned)
- Atlantean-Human Hybrids
- Faltine-Mhuruuk Hybrids (First appearance)
- Celestials (Mentioned)
- Earth-9997 (Main story and flashback)
- Earth (Main story and flashback)
- Africa (Main story and flashback)
- Earth Orbit
- North America
- Unnamed planet (Mentioned) (Destroyed)
- Earth (Main story and flashback)
- Vibranium (Main story and flashback)
- Panther Habit (Only in flashback)
- Heart-Shaped Herb (Only in flashback)
- Doctor Doom's Armor
- Panther Idol (First appearance)
- Cerebro (Mentioned)
- Captain America's Shield
- Iron maiden (Mentioned)
- Wizard Armor
- Cloak of Levitation
- Eye of Agamotto
- Cosmic Rays (Mentioned)
- Radioactive Spider (Mentioned)
Synopsis for "Earth X, Chapter 4"
Reed is speaking with T'Challa about stopping the mining of Vibranium, and T'Challa refuses. The wildlife of Wakanda has been transformed to be partially human and able to speak, and T'Challa believes they are the animal spirits, guiding him to make the right decisions.
Karnak tells Reed that his theory about the mutations is too perfect, and reality is never without flaws. Reed remembers Xavier's Cerebro, and proposes using it to find the rest of the Inhumans on the planet.
Cap confronts the Skull and his forces, only to be scoffed at and beaten as the Skull takes control over all the people around Cap, forcing him to fight people that do not want to fight him. The Skull also tells about the origin of Iron Maiden, and Spiders Man weaves an illusion on Cap, showing him that he is attacking Bucky back in World War II instead of attacking the Skull.
The Hydra attack another citizen on the streets of New York City, and are vanquished by Banner & Hulk, who have separated into two beings, a giant green ape-like monster who is mute and a boy with glasses. Bruce mistakes the citizen for Betty, and she is more afraid of the boy than the monster. They continue on to the Sanctum Sanctorum, meeting Clea, the now Sorceress Supreme.
- The cover to this issue features Storm (Ororo Munroe), (first appearance Giant-Size X-Men #1), Iron Maiden, Spiders Man, and Black Panther (T'Challa), (first appearance Fantastic Four #52.)
- Page 1-2: Covers early Wakanda history which was covered in (??)
- Page 3-4: Panel 1 shows Black Panther's father T'Chaka being shot dead by Ulysses Klaw, this event and the origin of the Black Panther were all originally covered in Fantastic Four #53. The costume Black Panther is wearing in panel 3 is circa his first appearance in Fantastic Four #52.
- Page 6: Panel 3 the "Hank" Reed Richards is speaking to (on the far right of the panel) is Hank McCoy, aka the Beast (First appearance Uncanny X-Men #1). Panel 5 we see the arm of Storm (Ororo Munroe.) Black Panther and Storm were also married in the Earth-616 universe in Black Panther #18.
- Page 12: In the final panel the movie that the Skull is commenting on "Oh yeah... That movie" is "The Ten Commandments" a 1952 film by Cecil B. DeMille that starred Charlston Heston.
- Page 13: Panel 3, "...You know like when Jack Nicholson did when he became the Joker?" is a reference to actor Jack Nicholson's role in Tim Burton's 1989 film "Batman", the film is of course named after the comic book character of the same name. Batman is one of the iconic characters owned by Marvel's long time rival DC Comics. Panel 4 when the Skull comments on the origins of Iron Maiden he quips "The name was my idea. I always loved that band." is a reference to the band Iron Maiden, a long time heavy metal band that was formed in 1975.
- Page 15-16: In panel 1 Cap is choking Bucky (James Barnes, first appearance Captain America Comics #1), who was Captain America's sidekick during World War II. Bucky was presumed killed in the line of duty as told in Avengers #4.
- Page 21: Panel 1 is the first appearance of Hulk & Banner in Earth X. The two used to be the same being and first appeared in Hulk #1. Panel 2, the Betty that Bruce is referencing here is his late wife Betty Ross Banner (First appearance Hulk #1) the two were married in Incredible Hulk #319. At the time Earth X was published, Betty Ross was believed dead in the mainstream Marvel Universe. She had "died" in Incredible Hulk #466. The appearance of "Betty" in these panels is reminiscent of a time when Betty herself was turned into a creature called "The Harpy" back in Incredible Hulk #168)
- Page 22: Panel 3 we first see Wong, he was Dr. Strange's manservant, he fist appeared in Strange Tales #110. Panel 6 we see Clea, once Dr. Stranges lover and apprentice. She first appeared in Strange Tales #126. In this panel she is wearing Strange's Cloak of Levitation and the Eye of Agamotto. Both were first given to Dr. Strange by the Ancient One in Strange Tales #127. The quote at the end of this issue was made by T.S. Eliot (Thomas Stearns Eliot, 1888-1965) who was a poet, dramatist and literary critic.