Syndrome is the main antagonist of the film. This supervillain was once Mr. Incredible's "biggest fan". In an attempt to earn his hero's respect, Buddy Pine tried to aid him in fighting crime as "Incredi-Boy", with gadgets he had invented in his spare time. Mr. Incredible declined Buddy's offer, and during a subsequent conflict between Mr. Incredible and the French supervillain Bomb Voyage, Buddy intervened, and ended up with a bomb attached to his costume. Incredible's attempt to remove it led to the destruction of a section of train tracks, which required him to save an approaching train. Angered with Buddy's carelessness, he handed him over to the police to be returned to his family.

Out of bitterness, Buddy recreated himself as an evil genius who plotted revenge on his former idol. In the scene where Syndrome confronted Mr. Incredible for the first time in fifteen years, Syndrome declared himself to be Incredible's nemesis. At one point, the DVD Director's Commentary seems to point out that his complete lack of conscience is a direct result of psychopathy, making him a mad scientist. Intensely amoral, he allowed missiles that he shot at an airplane carrying Helen, Dash, and Violet to continue on after Helen revealed the children's presence on the plane, bet Mirage's life in a subsequent showdown when Mr. Incredible threatened her, and carelessly threw behind himself a fully-loaded fuel tanker that could have endangered civilians. After his plans to fraudulently become a superhero and replace the supers that he had killed off were foiled by both the Incredibles and Frozone, Syndrome planned to abduct Jack-Jack and raise him as a sidekick, but failed due to the baby's recently emerged powers. Syndrome's cape got caught in his jet's intake and sucked him in. He was apparently killed by either the engine's blades or the subsequent explosion.

Syndrome has no superhuman powers, but he is incredibly intelligent, making him a super in his own right. He has invented numerous weapons, and high-tech vehicles that utilize such principles as robotics, anti-gravity, and zero-point energy, which he sold to black market buyers to make himself rich. He owns his own island, complete with a mansion, a sophisticated monorail system, missiles, and a staff of guards equipped with exotic vehicles of Syndrome's design.

- Wikipedia