Adam Sietz is an American actor, voice actor, comedian, writer, and producer with a career spanning stage, screen, and voice-over work for animation and video games. His birth name is Adam Lee Sietz, and he was born on February 14, 1966, in East Brunswick, New Jersey. He began his entertainment career at the age of nine, writing, co-directing, and starring in a school play. He is a co-founder of Big Hug Productions and Improvolutions.

Sietz has performed on Broadway three times and has appeared in numerous live-action television series, including multiple appearances on NBC's Law & Order. His film credits include roles in Woody Allen's Celebrity. As a comedian, he has worked with prominent figures such as Kevin Hart, Dave Chappelle, Chris Rock, and Jerry Seinfeld. In addition to his performance career, Sietz works as a consultant and coach specializing in humor and improvisational thinking, and he is the author of Unscripted Success with Improvisational Thinking.

In the realm of anime and animation voice acting, Adam Sietz is known for his work on several notable projects. He is a current voice cast member on MTV's Celebrity Deathmatch. In the Star Wars universe, he has voiced characters in the anime anthology series Star Wars: Visions, which was a collaboration between Disney+ and seven Japanese animation studios. For this series, he voiced the droid Dug in the episode The Duel, the character Musha in the episode Akakiri, and performed additional voice work for the episodes The Village Bride and another installment. Prior to this, he voiced characters named Mekks and Targen in the video game Star Wars: The Old Republic.

He has also performed voice work for the popular children's series Dora the Explorer and voiced the character Clifford the Big Red Dog before the role was taken over by John Ritter. His extensive video game voice credits include roles in major titles such as the Grand Theft Auto series, specifically Grand Theft Auto III, IV, and V, as well as Bioshock. In the series Go! Go! Loser Ranger!, Sietz provides the voice for the character Peltrola.

Throughout his career, Sietz has received several awards. He is an Emmy Award winner, having received a special achievement Emmy in 1986 for writing and creating segments for broadcasts of the New York Mets baseball team. He has also been recognized as an award-winning comedian and actor.