Stuart Zagnit is an American actor best known as the original English voice of Professor Samuel Oak in the Pokémon anime franchise. Born on March 28, 1952, Zagnit sometimes works under the stage name Stan Hart.

Zagnit began his tenure as Professor Oak when the English dub of Pokémon first aired, originating the role and continuing to voice the character for over eight years, appearing in more than 400 episodes. His run as Oak covered the original Pokémon series and extended into Pokémon Chronicles and the Pokémon Advanced Generation series, which includes the seasons commonly referred to as Pokémon Advance. During this time, he also voiced the character in several related media projects, including the theatrical films Pokémon 2000 and Pokémon 3, as well as the video games Pokémon Snap and Pokémon Puzzle League.

In addition to Professor Oak, Zagnit voiced the Kanto Gym Leader Koga in the original series and later returned to the Pokémon franchise in 2012 to voice Cedric Juniper, Professor Junipers father, during the Pokémon: Black and White arc. He has cited his improvisation of the line Ooh, my lumbago in Pokémon 2000 as a memorable creative contribution to the role.

Beyond Pokémon, Zagnits anime voice acting credits include Zolf in The Slayers, Dr. Hidezaburo Kitaguchi and Admiral Yutta Do Lonawer in The Irresponsible Captain Tylor, and Chin Tao in Shaman King. He also provided voices for the English adaptations of Baki the Grappler, Teenage Mutant Ninja Turtles, Winx Club, and Mission Odyssey. His work in the industry has primarily been with New York-based dubbing studios such as 4Kids Entertainment, DuArt Film and Video, and TAJ Productions.

Zagnit has a substantial background in theatre, considering himself primarily a stage actor. His Broadway credits include Seymour in Little Shop of Horrors, the Mayor of Whoville in the original run of Seussical, and the Wizard in Wicked. He has also appeared in touring productions of Fiddler on the Roof and The Producers. His on-screen television appearances include guest roles on Law and Order, 30 Rock, Elementary, and The Good Wife.

In 2006, production of the English Pokémon dub shifted from 4Kids Entertainment to The Pokémon Company, resulting in Zagnit and several other original cast members, including Ash Ketchum voice actress Veronica Taylor, being recast. He has reflected that the experience was painful but that his connection with the character remained strong. In 2025, Zagnit returned to the role of a professor character inspired by Oak for the off-Broadway musical parody Balls: The Monster-Catchin Musical Comédy.