Crystal -- an Inhuman with the ability to psionically control the four classical elements: earth, fire, air, and water -- was first introduced, along with the rest of the Inhuman Royal Family, in the pages of The Fantastic Four. She immediately fell in love with Johnny Storm and became the first character to join the Fantastic Four (outside of its original members) when Sue Richards went on maternity leave.

In 1991, Marvel rebooted The X-Men with four variant covers and a special gatefold cover combining all four versions. X-Men #1 (Vol. 2) sold over 8.1 million copies, making it the best-selling comic book of all-time.

In his 1954 book Seduction of the Innocent, German-American psychiatrist Fredric Wertham warned that comic books were a serious cause of juvenile delinquency. The book was taken seriously at the time, and was a minor bestseller that created quite a stir among alarmed parents. As a result, a U.S. Congressional inquiry was launched into the comic book industry. In response, comic book publishers voluntarily established the Comics Code Authority to self-censor their titles.

Plastic Man's sidekick is Wolfgang "Woozy" Winks. In his first appearance (November 1942), Woozy saves a wizard from drowning, and is rewarded with a spell that causes the forces of nature to protect him whenever he is in danger. Later stories ignore this ability, and Woozy simply becomes Plastic Man's inept assistant.

She-Hulk has been a member of the Avengers, the Fantastic Four, Heroes for Hire, the Defenders, Fantastic Force, and S.H.I.E.L.D. She has NOT been a member of the Guardians of the Galaxy.

The Sanctum Sanctorum is the residence of Doctor Strange. The building first appeared in Strange Tales #110 (July 1963) and is located at 177A Bleecker Street in New York City's Greenwich Village neighborhood, a reference to the address of an apartment once shared by writers Roy Thomas and Gary Friedrich.

Stan Lee originally wanted the Hulk to be grey because he wanted a color that wouldn't suggest any particular ethnic group, but colorist Stan Goldberg had problems with the grey coloring, resulting in different shades of grey, and even green, in the first issue. The Hulk's color was subsequently changed to a more manageable green, and the original color was explained away as a second Hulk persona that is usually suppressed by the stronger Green Hulk.

Ally Sloper's Half Holiday was a British comics magazine, first published on 3 May 1884. It featured Ally Sloper, a blustery, lazy schemer often found "sloping" through alleys to avoid his landlord and other creditors, and is considered by most comics historians to be the first comic strip magazine to feature a recurring character.

After Princess Fen of Atlantis mated with the human sea captain Leonard McKenzie, she gave birth to the first human/Atlantean hybrid: Namor, the Sub-Mariner.

The founding members of the X-Men were Cyclops, Marvel Girl, Beast, Angel, and Iceman. Wolverine didn't join the team until Giant-Size X-Men #1 (1975), but he quickly made up for lost time, becoming the most popular X-Men character and eventually earning his own comic.