Seth (セス, Sesu) is a fictional character in Capcom’s Street Fighter fighting game series. First introduced in Street Fighter IV, he is the final boss of the game and its subsequent updates. He is the chief executive officer of the Shadaloo Intimidation Network (S.I.N.), the weapons division of the Shadaloo terrorist organization in the game’s narrative. His body has been heavily modified using advanced technology, with a device installed in his abdomen called the “Tanden Engine”. Other appearances by Seth include Project X Zone and Street Fighter V. Seth is voiced by Akio Ōtsuka in Japanese, and Michael McConnohie in English.
As a boss character in Street Fighter IV, Seth is not particularly popular with video game journalists, and had been criticized for the lack of originality behind his character design as well as unfair difficulty. On the other hand, Seth’s return in Street Fighter V along with the character’s visual overhaul has been received more positively.
Within the Street Fighter universe, Seth is created using fighting data from the world’s best fighters, which enables him to copy techniques used by other characters, such as Guile’s Sonic Boom and Zangief’s Spinning Piledriver. Ryota Niitsuma, assistant producer of the arcade version of Street Fighter IV, acknowledged that Seth was overpowered and was stronger then Capcom had anticipated following the launch of Street Fighter IV, and later updates for the game would tweak him to be more balanced.
For Street Fighter V, Seth is given a completely new moveset, but maintains his ability to mimic his opponents; Capcom USA employee Dan Louie explained that this is intended to make Seth “feel familiar and fresh at the same time” to players. His playstyle in each match differs not only based on the V-Skill or V-Trigger the player chooses, but will also be different based on their opponent in the case of Seth’s V-Skill I. Seth is capable of stealing moves from all 40 characters in the roster of Street Fighter V as of season 4, meaning he can even steal a special move from another Seth. Seth also uses the Tanden Engine for a special move, his super combo, and both of his ultra combos.
Description by Wikipedia