SVU Episode You Forgot Starred John Stamos

Since its premiere in 1999, "Law & Order: SVU" has skyrocketed to major popularity, making the NBC procedural series the longest-running primetime drama (via NBC). Tons of celebrities have stepped into various roles as guest stars on the show, and many end up portraying villains — often shocking audiences who are used to seeing them in more wholesome roles.

Examples include "Hunger Games" star Elizabeth Banks, who plays a murderous porn star in Season 3; Henry Winkler of "Happy Days," who portrays a husband who steals from his wife in Season 3; and Ian Somerhalder of "The Vampire Diaries," who plays a serial killer and rapist in Season 4 (via Insider).

Likewise, on May 4, 2011, John Stamos appeared as a criminal on "SVU." Fans who know and love him as Uncle Jesse on "Full House" and "Fuller House" were surprised by the actor's sinister performance.