Seth (セス) is the main antagonist of Street Fighter IV. He is the head of Shadaloo's weapon division, S.I.N. According to the official Street Fighter website, Seth is one of many genetically engineered replacement bodies for Vega.
Seth is the 15th of 26 enhanced beings that use data collected from the world warriors to create a deadly style of mixed martial arts. Seth claims to be superior as a result of his humanity while the others are merely puppets. His storyline indicates that he plans to control the remnants of Shadaloo through S.I.N after Vega's apparent death at the hands of Gouki in Street Fighter II. He also attempts to manipulate Juri Han, a woman who possesses a bionic eye he created. She confronts him and unexpectedly offers to work for him, to which he agrees. He hosts a World Warrior tournament in hopes of luring Ryu to complete his BLECE project, but is dismayed at reports that Vega has once again returned from death. Vega finally encounters Seth and defeats him in combat, and afterwards tells him that in fact everything that has happened has gone according to Vega's plan. After Vega leaves, Juri tells Seth that she intentionally pitted the two against each other, but is disappointed that Seth was not more of a challenge for Vega. Afterwards, Ryu would encounter another Seth and defeat him and destroy the BLECE machine. Vega commands the remaining copies of Seth and they wreak havoc on the fighters in and around the S.I.N. compound, as many of the characters' endings depict them defeating a version of Seth.
Seth returns in Street Fighter V: Champion Edition. With his body destroyed at the end of Street Fighter IV, his surviving brain is combined with the body of a Shadaloo Doll named Unit Zero, resulting in Seth adapting a new female appearance.
- Tanden Engine
- Tanden Storm
- Tanden Stream
- Tanden Typhoon