The Sinister Syndicate is a group of supervillains appearing in American comic books published by Marvel Comics. The characters serve as a collection of lesser-known Spider-Man villains. The group was the focus of the 1991 Deadly Foes of Spider-Man mini-series.

The Sinister Six are a group of supervillains appearing in American comic books published by Marvel Comics, mainly those featuring Spider-Man. The members are drawn from the character's list of enemies, with the original members forming the team in The Amazing Spider-Man Annual #1. Led by Doctor Octopus, the team in its premiere followed swiftly the very early appearances of many of the most enduring members of Spider-Man's rogue's gallery: Vulture, Sandman, Electro, Mysterio, and Kraven the Hunter. While Doctor Octopus has generally remained its leader, the Sinister Six has had multiple variations of composition.