Sergeant Yates, voiced by Trey Parker, is a character in South Park. He is an inept Irish-American police officer. He plays the general role of an officer, taking part in various investigations and situations. He is somewhat gullible and believes in the supernatural, and often wastes time by conducting extremely trivial investigations. When Michael Jackson, known as Mr. Jefferson, moves into South Park and it is revealed that Yates hates all black men wealthier than himself and frames them—as Mark Fuhrman was accused of doing to O.J. Simpson—but panics and becomes disillusioned when he realizes "Mr. Jefferson" is black despite his "white appearance." He discovers Mr. Jefferson is indeed black, but when Mr. Jefferson decides he will give away all of his money, Yates lets him go, having no need to put poor black men in jail.
In "Pre-School", Sergeant Yates arrests Trent Boyett when the boys accuse Trent of setting the former Pre-School teacher Mrs. Claridge on fire (again). The unresponsive Mrs. Claridge tried to tell Yates that Trent was not responsible (by beeping twice for "no" on her iron lung), but he misinterprets this as "yes, yes" and arrests the innocent Trent, landing him in juvenile hall once again.
In "Miss Teacher Bangs a Boy", Kyle reports to Yates and the cops that the Kindergarten teacher, Ms. Stevenson, is in a relationship with his younger brother Ike. It is shown that Yates and his pals do not see anything wrong with women committing sex crimes like this one, and at one point remarked that he would have gladly hooked up with a sexed-up teacher when he was a kid. He proves to be more of a hindrance than anything else to the case.
In Butter's Bottom Bitch, he went undercover as a prostitute. Though it was obvious when he was dressed up as a woman he was a man, no one seemed to notice this. He also is unaware of the fact he doesn't need to have sex with the Johns to arrest them for soliciting prostitution, something that creeps out the rest of his squad.
He is married to Maggie Yates, who shares his views on rich black men. Ironically in Butter's Bottom Bitch he marries a rich black man. However, at the end of the episode, he pulls out his badge and gun and threatens his "Daddy" with them that he is a cop. He also married the black guy as part of his guise to end prostitution in South Park.