Spencer Smythe () is a fictional supervillain appearing in American comic books published by Marvel Comics, usually as an adversary of the superhero Spider-Man. A scientist researching robotics and arachnids, he turned to crime to finance his research, and dedicated his life to capturing Spider-Man. Smythe is best known for creating the Spider-Slayers, robots designed specifically to hunt down, capture, or kill the web-slinger. He is also the father of Alistair Smythe, who inherited Spencer's creations and hatred for Spider-Man after his death.