Season One of MTV's Teen Wolf contains twelve episodes which aired over the course of three months, beginning on June 5, 2011 and concluding on August 15, 2011.
- Tyler Posey as Scott McCall: a young and new Omega werewolf
- Crystal Reed as Allison Argent: daughter of werewolf-hunters and Scott's love interest.
- Dylan O'Brien as Stiles Stilinski: Scott's trusted and loyal human best friend.
- Tyler Hoechlin as Derek Hale: a Beta werewolf and Scott's werewolf mentor.
- Holland Roden as Lydia Martin: Allison's best friend and the girlfriend of Jackson.
- Colton Haynes as Jackson Whittemore: co-captain of the lacrosse team, Lydia's boyfriend and Scott's rival.
- Linden Ashby as Sheriff Stilinski: Stiles' father and the sheriff of Beacon Hills. (10 episodes)
- JR Bourne as Chris Argent: Allison's father and a werewolf-hunter. (10 episodes)
- Jill Wagner as Kate Argent: Allison's aunt, werewolf-hunter, and an antagonist. (8 episodes)
- Melissa Ponzio as Melissa McCall: Scott's mother and a nurse at Beacon Hills High School. (8 episodes)
- Keahu Kahuanui as Danny Mahealani: Jackson's openly gay best friend.
- Orny Adams as Bobby Finstock: the coach of the Beacon Hills High lacrosse team. (7 episodes)
- Seth Gilliam as Dr. Alan Deaton: a veterinarian, Scott's boss, and a guide to the supernatural. (6 episodes)
- Ian Boehn as Peter Hale: Derek's uncle, an Alpha werewolf, and the main antagonist. (6 episodes)
- Eaddy Mays as Victoria Argent: Allison's mother and a werewolf-hunter. (5 episodes)
- Adam Fristoe as Adrian R. Harris: Scott's chemistry teacher. (5 episodes)
- Haley Roe Murphy as Laura Hale: Derek's deceased sister who was killed by Peter to obtain her Alpha status while investigating the arsonist behind the Hale House fire.
- Michael Dane as Levesque: a werewolf-hunter.
- JayR Kalis as Ulrich: a werewolf-hunter.
- Adam C. Edwards as Tyhurst: a state detective and werewolf-hunter.
- Jamila Thompson as Harley: an acquaintance of Scott and Stiles in the pilot episode.
- John Curran as Garrison Myers: a bus driver and one of the arsonists of the Hale House fire.
- Hajji Golgithy as Reddick: an arsonist, killed by Peter.
- Johnathan Kleitman as Unger: an arsonist, killed by Peter.
- Robert Pralgo as Mr. Whittemore: Jackson's adopted father.
- Carrie Kroll as Mrs. Whittemore: Jackson's adopted mother.
- Jeff Rose as Mr. Martin: Lydia's father.
- Susan Walters as Mrs. Martin: Lydia's mather.
- Desiree Hall as Jeniffer: Peter's nurse, killed by Peter.