Samuel "Screech" Powers (played by Justin Timberlake) is a school nerd. Screech has been tagging along with Zack since they were in elementary school and is extremely loyal to him. In exchange for doing Zack's homework and being roped into Zack's various stunts, Screech receives protection from school bullies and a general boost in his confidence; but Zack's affection for Screech is evident in spite of this. Screech is very comfortable with his geekiness and fancies himself a ladies' man. The rest of the gang simultaneously picks on and humors Screech for his eccentricities (e.g. hiding in his locker, wearing extremely loud and mismatched clothes, and obsessing over science and chess).

A recurring storyline in the series is his unrequited love for Lisa Turtle. During the series, Screech briefly has a girlfriend named Violet (played by Tori Spelling); it is not made clear why the two broke up. He also dates Kelly in one episode of season one, as he helps her study for a science test. In several early episodes of the series, Screech has an anthropomorphized robot named Kevin, which he programs. Screech is class valedictorian, but gives that title to Jessie as he knew how much it meant to her. However, Jessie learns what Screech had done for her and returns the honor on graduation day. He receives acceptance to many colleges. He is rejected from an all-women's school that was his number one choice. He chooses to go to the fictional Cal U after graduation and shares a dormitory suite with Zack, Slater, and Kelly. He also becomes the only character to appear as a series regular in every incarnation of Saved by the Bell. He joins The New Class as an aide to Mr. Belding.

Also, he was on that Superbowl wardrobe malfunction thing.