Benjamin "Ben" Reilly, also known as the Scarlet Spider, is a superhero appearing in American comic books published by Marvel Comics. Grown in a lab by Miles Warren/Jackal, he is a clone of Peter Parker/Spider-Man tasked with fighting him but instead becoming an ally, later even regarded as a "brother". Created by writer Gerry Conway, the character first appeared in The Amazing Spider-Man #149 and is seemingly killed in the same issue. The character returned and featured prominently in the 1994–96 "Clone Saga" storyline, adopting the "Scarlet Spider" alias with a costume similar to Spider-Man's consisting of a red spandex bodysuit and mask complemented by a blue sleeveless hoodie sweatshirt adorned with a large spider symbol on both sides, along with a utility belt and bulkier web-shooters. This Scarlet Spider costume was designed by artist Tom Lyle. When Peter Parker temporarily left the Spider-Man role, Ben became the new Spider-Man while wearing a new costume variation designed by artist Mark Bagley. However, Reilly dies at the hands of Norman Osborn/Green Goblin, sacrificing himself to save Parker who then resumes the Spider-Man role.

The Scarlet Spider is an alias used by several fictional characters appearing in American comic books published by Marvel Comics, most notably Ben Reilly and Kaine Parker, both of whom are genetic replicates of the superhero Spider-Man.