Season One

Season One of Glee first aired on September 21, 2009, four months after the Pilot was broadcasted on May 19, 2009. The season officially concluded on June 8, 2010.

The series focuses on a high school Glee Club called the New Directions, set within the fictional William McKinley High School in Lima, Ohio.

Major themes of Season One included the characters' desires to escape the confines of small-town Ohio life and make an impact on the world rather than remaining a "Lima Loser." Many of the story arcs, most notably Quinn's pregnancy and the New Directions' rivalry with Carmel High's Glee Club Vocal Adrenaline, are related to this concept. The other major motif of season one was the characters concealing and revealing their true selves. This includes major events like the blossoming romance between Finn and Rachel, Quinn's lies about her child's father, Kurt's coming out, and Terri's fake pregnancy.

Dianna Agron (Quinn Fabray), Chris Colfer (Kurt Hummel), Jessalyn Gilsig (Terri Del Monico), Jane Lynch (Sue Sylvester), Jayma Mays (Emma Pillsbury), Kevin McHale (Artie Abrams), Lea Michele (Rachel Berry), Cory Monteith (Finn Hudson), Matthew Morrison (Will Schuester), Amber Riley (Mercedes Jones), Mark Salling (Noah Puckerman), and Jenna Ushkowitz (Tina Cohen-Chang) were introduced as the main casts in this season. It made them the original main cast of Glee.

Main Cast

 * Dianna Agron as Quinn Fabray (22/22)
 * Chris Colfer as Kurt Hummel (22/22)
 * Kevin McHale as Artie Abrams (22/22)
 * Lea Michele as Rachel Berry (22/22)
 * Cory Monteith as Finn Hudson (22/22)
 * Matthew Morrison as Will Schuester (22/22)
 * Amber Riley as Mercedes Jones (22/22)
 * Mark Salling as Noah Puckerman (22/22)
 * Jenna Ushkowitz as Tina Cohen-Chang (22/22)
 * Jane Lynch as Sue Sylvester (20/22)  (episodes 1-9, 11-19, 21-22)
 * Jayma Mays as Emma Pillsbury (16/22)  (episodes 1-6, 8, 10-15, 17, 19, 22)
 * Jessalyn Gilsig as Terri Del Monico (13/22)  (episodes 1-7, 10-14, 21)

Special Guest Stars

 * Jonathan Groff as Jesse St. James (7/22)  (episodes 14-17, 19, 21-22)
 * Idina Menzel as Shelby Corcoran (5/22)  (episodes 14, 19-22)
 * Kristin Chenoweth as April Rhodes (2/22)  (episodes 5, 16)
 * Eve as Grace Hitchens (2/22)  (episodes 11, 13)
 * Josh Groban as himself (2/22)  (episodes 3, 22)
 * Olivia Newton-John as herself (2/22)  (episodes 17, 22)
 * Molly Shannon as Brenda Castle (2/22)  (episodes 17, 19)
 * Neil Patrick Harris as Bryan Ryan (1/22)  (episode 19)
 * Michelle Grigg as Ashley Ryan (1/22) (episode 19)
 * John Michael Higgins as Russell (1/22)  (episode 19)

Guest Stars

 * Naya Rivera as Santana Lopez (22/22)
 * Heather Morris as Brittany Pierce (21/22) (episodes 2-22)
 * Harry Shum Jr. as Mike Chang (19/22)  (episodes 4-22)
 * Dijon Talton as Matt Rutherford (18/22)  (episodes 4-9, 11-22)
 * Iqbal Theba as Principal Figgins (17/22)  (episodes 1-7, 9, 12-15, 17, 19-22)
 * Patrick Gallagher as Ken Tanaka (10/22)  (episodes 1-4, 6, 8, 12-14, 17)
 * Josh Sussman as Jacob Ben Israel (10/22)  (episodes 2, 5, 7, 9, 13-15, 18, 20-21)
 * Stephen Tobolowsky as Sandy Ryerson (7/22)  (episodes 1, 3-5, 9, 17, 21)
 * Max Adler as Dave Karofsky (5/22)  (episodes 8, 12, 14, 17, 20)
 * James Earl III as Azimio Adams (5/22)  (episodes 8, 12, 14, 17, 20)
 * Mike O'Malley as Burt Hummel (5/22)  (episodes 4, 9, 16, 18, 20)
 * Romy Rosemont as Carole Hudson-Hummel (5/22)  (episodes 1, 2, 10, 16, 20)

Co-Stars

 * Kent Avenido as Howard Bamboo (4/22)  (episodes 1, 3, 6, 21)
 * Ashley Fink as Lauren Zizes (4/22)  (episodes 9, 14, 18, 20)
 * Lauren Potter as Becky Jackson (4/22)  (episodes 9, 12, 15-16)
 * Robin Trocki as Jean Sylvester (2/22)  (episodes 9, 17)

Major Events

 * Finn and Quinn relationship, Finn and Rachel relationship, and Quinn and Puck relationship, and thus arising the Finn/Quinn/Rachel love triangle and Finn/Puck/Quinn love triangle.
 * Quinn's teen pregnancy. She insists that Finn is the father, but it's actually Puck.
 * Rachel's feelings for Finn.
 * Rachel meeting her biological mother, Shelby.
 * Rachel and Jesse relationship and Finn/Jesse/Rachel love triangle. Jesse joining New Directions, then abruptly quitting.
 * Will bringing in members and keeping the team together in the first half.
 * Terri's fake pregnancy leading to Will and Terri's divorce.
 * Will and Emma relationship.
 * Ken and Emma's failed wedding plan.
 * Kurt coming to terms with his sexuality.
 * Kurt and his relationship with his father, Burt, about his sexuality.
 * Kurt's feelings for Finn.
 * Kurt arranges Burt and Carole relationship to make him closer to Finn.
 * The relationship of Tina and Artie.
 * The friendship of Kurt and Mercedes.
 * Kurt and Mercedes join the Cheerios, leading Mercedes to not being herself. Puck takes advantage of Mercedes' new popularity after he shaves his mohawk, creating Puck and Mercedes relationship.
 * Will and Sue's rivalry.
 * New Directions and Vocal Adrenaline rivalry.
 * New Directions lose Regionals, but are given another year thanks to Sue.

Trivia

 * Dianna Agron, Chris Colfer, Kevin McHale, Lea Michele, Cory Monteith, Matthew Morrison, Amber Riley, Naya Rivera, Mark Salling, and Jenna Ushkowitz are in all the episodes.
 * Naya Rivera was present in all episodes, though she was a recurring character.
 * This is the only season:
 * Not to feature any original songs.
 * Santana didn't have a solo.
 * Matt appears as a member of New Directions.
 * Brittany didn't sing lead in a song.
 * Rachel was not seen with bangs.
 * Nobody is rejected from the New Directions.
 * Not to feature any New York scenes.
 * Not to feature Blaine, Sam, Shannon, or the Dalton Academy Warblers.
 * Not to feature a Klaine duet.
 * Brittany didn't perform a duet.