Benjamin "Ben" Reilly, also known as the Scarlet Spider, is a major character in the Spider-Man franchise. He appears in American comic books published by Marvel Comics. He is the titular deuteragonist of the Clone Saga story arc. He was created by Gerry Conway and Ross Andru. He first appeared in The Amazing Spider-Man #149 in October 1975.

He is a clone, ally and "brother" of Peter Parker / Spider-Man that assumed the identity of the Scarlet Spider and later the second Spider-Man shortly before his first death. Reilly has been resurrected and killed many times in the years since.

The character made his cinematic debut in the 2023 feature movie Spider-Man: Across the Spider-Verse voiced by Andy Samberg, and will make his live-action debut in the 2025 Amazon Prime Video streaming television series Spider-Noir, as a composite character with Spider-Man Noir, portrayed by Nicolas Cage.