Sadler (サドラー Sadorā?) is a character who appears exclusively as the main villain of Street Fighter Alpha: The Animation. He is an enigmatic biologist funded by Shadaloo. He seeks to become the greatest fighter ever by stealing ki (or "data") from various street fighters all over the world, and is not above killing innocent people to achieve this.
Sadler learns of a fighter named Ryu who defeated the Muay Thai champion, Sagat, and becomes fascinated with Ryu's dark power, particularly his connection to his Satsui no Hado. In order to obtain this power and use it to further his goal of world domination, Sadler employs a young boy named Shun to meet Ryu and pose as his younger brother. With help from his android enforcer, Rosanov, Sadler stages a kidnapping of Shun in order to lure Ryu to his hideout. Chun-Li brings Ryu, Ken, and a group of fighters (Dhalsim, Dan, Birdie, Adon, Sodom, Guy and Rolento) to help her find Shun and bring down Shadaloo.
Sadler has Chun-Li's group fight each other, and selects Birdie for the "prize", having his men lure him into the hideout and place him inside a machine to strip him of his power. Ken and Chun-Li get wind of this upon seeing Sadler's personal victims, and rush inside to free the others. Sadler then orders Rosanov to absorb Shun, defeat the others and fight Ryu, goading him into succumbing to the Dark Hado, all the while having Rosanov connected to a machine which will feed Sadler's body with energy every time Ryu hits Rosanov.
Finally, Ryu loses total control of himself and strikes Rosanov with a Metsu Hadoken, destroying him and freeing Shun, but badly injuring himself in the process - as well as giving Sadler the data he desired.
With his power skyrocketing, Sadler emerges from his facility and fights Ryu head on with the dark power that he drained from him, easily gaining the upper hand. However, with help from Ken, Ryu manages to survive Sadler's attacks through willpower, and blasts the power-hungry madman with a Shinku Hadoken. The attack leaves Sadler badly damaged, and before he can openly wonder how Ryu's power can still be superior to his, Sadler crumbles into dust and perishes.