Moon Knight is a superhero appearing in American comic books published by Marvel Comics. Created by writer Doug Moench and artist Don Perlin, the character first appeared in Werewolf by Night #32 (August 1975).

The son of a rabbi, Marc Spector served as a Force Recon Marine and briefly as a CIA operative before becoming a mercenary alongside his friend Jean-Paul "Frenchie" DuChamp. He is killed by Raoul Bushman, but the god Khonshu resurrects him as his avatar. After returning to the United States, Spector becomes the crimefighter Moon Knight, aided by Frenchie and Marlene Alraune, who becomes his lover. Along with his costumed alter ego, he uses three other identities to gain information: billionaire businessman Steven Grant, taxicab driver Jake Lockley, and suited detective and police consultant Mr. Knight. It is later revealed Moon Knight has dissociative identity disorder and that the Grant and Lockley alters emerged during his childhood.

In most depictions, Moon Knight has no abilities beyond his athleticism and detective skills. For a time, he had superhuman strength and durability derived from the phases of the moon, but this ability later vanished.

The character has made appearances in various media outside of comics, including animated series and video games. Oscar Isaac portrays the character in the Marvel Cinematic Universe series Moon Knight (2022).

In an interview, Doug Moench recalled the character's genesis: "Somebody mentioned in the office and suggested using The Committee, and that I should bring The Committee back, and then I found out who The Committee were and thought, well they're really boring, I don't wanna use them. And then I thought, well wait a minute, how about if The Committee hires a mercenary to kill the Werewolf. And I thought, yeah that's a good idea, then I create this new character and it won't be these boring guys in business suits, it would be a flashy character. So, I said who is best to kill the Werewolf? Well, someone who uses silver weapons because silver hurts the Werewolf. And tied to the night, because the Werewolf only comes out at night, and I'll base this character on the Moon, because the Moon makes the Werewolf change, and this is going to be the opposite of the Werewolf, and as soon as I said the Moon I said, ooh I'll have a costume that's just like the Moon, just black and white, jet and silver, no color on the costume."

Don Perlin also commented on the creation of the character, "We were told we needed a costumed character in the book. So Doug and I created Moon Knight. I wanted the costume to be just black and white. Since he'd be on a color page, that would make him a little bit different. He had a silver baton he could use when he battled werewolves. See, he was hired to track down to kill the Werewolf."

The character debuted in Werewolf by Night #32 (August 1975), written by Doug Moench with art by Don Perlin and Al Milgrom, as a mercenary hired by the Committee to capture the title character. The creative team gave Moon Knight moon-related symbols and silver weapons (a metal poisonous to a werewolf) to mark him as a suitable antagonist for the werewolf hero. The two-part story continues into #33, when Moon Knight realizes Russell is a victim rather than a monster and decides to help him. A demonic vision of Moon Knight then appeared in Werewolf by Night #37 (March 1976).

Editors Marv Wolfman and Len Wein liked the character and decided to give him a solo story in Marvel Spotlight #28–29 (June/August 1976), again written by Doug Moench with art by Don Perlin. The story, along with Spectacular Spider-Man #22–23 (September/October 1978) written by Bill Mantlo, recast Moon Knight as a more heroic character. His association with the evil Committee during his first appearance was retconned to be an undercover mission he undertook to learn more about the villains. Moon Knight acted as a hero again in Marvel Two-in-One #52, written by Steven Grant with art by Jim Craig. In The Defenders #47–51, Moon Knight briefly joined the Defenders during their war against the Zodiac Cartel.