MacDonald "Mac" Gargan is a supervillain appearing in American comic books published by Marvel Comics. Created by writer Stan Lee and artist Steve Ditko, the character first appeared in The Amazing Spider-Man #19 (December 1964). Mac Gargan is a recurring antagonist of the superhero Peter Parker / Spider-Man. He debuted as a private investigator hired by J. Jonah Jameson to learn how Peter Parker took pictures of Spider-Man. In the following issue, Jameson decided to turn Gargan into a deadly adversary for Spider-Man through a barely-tested procedure, which left Gargan with a scorpion-themed armor and the predatory instincts of the arachnid. Driven insane by his mutation, Gargan instead turned to a life of crime as the Scorpion, and went on to menace both Spider-Man and Jameson, who he held responsible for his transformation. Since then, having finally removed the armor, Gargan has also served as the third host of the Venom symbiote, and a member of the Dark Avengers as Spider-Man, but eventually returned to his Scorpion alias as it kept him alive due to the strain both the neural-armors and symbiote put on his body.

Since his original introduction during the Silver Age of Comic Books, the character has been featured in various other Marvel-licensed products, including feature films, television series, video games, and merchandise. Michael Mando portrays the character in the Marvel Cinematic Universe (MCU) films Spider-Man: Homecoming (2017) and Spider-Man: Brand New Day (2026), while an alternate version of the character appeared in animated form in the Disney+ series Your Friendly Neighborhood Spider-Man (2025).

Mac Gargan debuted in The Amazing Spider-Man #19 (December 1964), created by writer Stan Lee and artist Steve Ditko. He later appeared under the codename of Scorpion in The Amazing Spider-Man #20 (January 1965). He appeared as an antagonist in the 1977 Ms. Marvel series.

Mac Gargan appeared as the third Venom in Marvel Knights: Spider-Man #10 (January 12, 2005). He later appeared as the third Spider-Man in Dark Avengers #1 (January 21, 2009). He appeared as a regular character in the series from issue #1 through issue #16 (May 12, 2010). He appeared in the 2009 Dark Reign: Sinister Spider-Man series, his first solo comic book series, by writer Brian Reed and artist Chris Bachalo. According to Diamond Comic Distributors, Dark Reign: Sinister Spider-Man #1 was the 45th best selling comic book in June 2009. Dark Reign: Sinister Spider-Man #2 was the 68th best selling comic book in July 2009.

Mac Gargan reappeared under the codename Scorpion in the "Big Time" story arc from the 2010 The Amazing Spider-Man series. He appeared in the 2019 Absolute Carnage series.

Mac Gargan appeared in the 2020 Ravencroft series. He appeared in the 2022 Miles Morales: Spider-Man series.

Mac Gargan was a private investigator initially hired by J. Jonah Jameson to find out how Peter Parker is able to obtain incredible pictures of Spider-Man. Gargan's efforts set off Peter's spider-sense and the teen easily evades the detective. Jameson then decides to hire Gargan as the subject of a barely-tested process that would endow him with the useful characteristics of a particular animal with the help of Farley Stillwell. Stillwell also outfits him with a club-like mechanical tail. In this case, a scorpion is the base for the purposes of creating a powerful agent capable of defeating Spider-Man as the scorpion is a predator of the spider. The Scorpion proves to be more than a match for Spider-Man, defeating him twice, but the mutagenic treatment seriously affects Gargan's mind, driving him insane as the predatory instincts of the scorpion take over. He promptly turns on his benefactor but Spider-Man intervenes, and finally defeats the Scorpion in their third battle. The Scorpion becomes a professional criminal and returns to indulge in a vendetta against Spider-Man and Jameson, only to be defeated again.

He is later hired by a spy ring to follow S.H.I.E.L.D. agent Sharon Carter, but is defeated by Captain America. Scorpion is acquired by Mr. Kline, who creates an android duplicate of him. The real Scorpion and Mr. Hyde launch a campaign of terror against S.H.I.E.L.D. agents, but are defeated by Captain America and Falcon. After being released from prison for good behavior, the Scorpion hunts down Spider-Man and tries drowning him in a cement vat, hoping to use the boost to his reputation to become an underworld boss. Scorpion learns that Spider-Man survived the encounter, and the Jackal gives him the hero's location. The Scorpion arrives at a hospital room with Peter Parker and his Aunt May. Not recognizing Spider-Man in his civilian identity, he threatens May and demands to know where Spider-Man is. After she faints, Scorpion rampages through the hospital. A furious Spider-Man beats the Scorpion and makes him apologize to May.