American Idol's Adam Lambert guest stars as Elliot -- aka "Starchild" -- an aspiring singer who auditions for Kurt's (Chris Colfer) indie band during season five.
Photo by: Mike Yarish/FOX
Demi Lovato guest stars as Dani, a love interest for Naya Rivera's Santana, during season five.
Photo by: Jennifer Clasen/FOX
Patty Duke and Meredith Baxter
Jewelry store owner Patty Duke helps Blaine (Darren Criss) shop for a ring in the season four finale and hits it off with the high school senior, setting up a double date for Blaine and Kurt with her and partner -- played by Meredith Baxter.
Photo by: Adam Rose/FOX
The Sons of Anarchy star plays Nancy Abrams, Artie's (Kevin McHale) mother. The casting marks a wish fulfillment for McHale, who said last summer at Comic-Con that he envisioned the Married … With Children and Futurama star to fill the role -- with Glee co-creator Ian Brennan already having story ideas.
Photo by: Eddy Chen/FOX
American Idol runner-up Jessica Sanchez plays the lead singer for New Directions' rival, Frida Romero and arrives as the rag-tag club looks to be competitive at Regionals in the fourth-season finale. "It's pretty intimidating for New Directions," co-star Chord Overstreet said of listening to Sanchez sing on set. "She's big weapon for her squad and we're not really prepared for that. But I think we'll hold our own, but it's definitely something where we're all freaking out and scrambling at the last minute."
Photo by: Getty Images
Kate Hudson will begin her multiple-episode guest stint in the Season 4 premiere as a NYADA dance instructor for Lea Michele's Rachel.
Photo by: Getty Images
Sarah Jessica Parker
Former Sex and the City star Sarah Jessica Parker will join Glee early on during its fourth season.
Gwyneth Paltrow picked up a supporting actress in a comedy Emmy for her role as McKinley substitute teacher Holly Holliday. Her cover of Cee Lo Green's "Forget You" ranks as one of the show's most-downloaded songs, with more than 720,000.
Little Package, Big Threat
Charice played Sunshine Corazon, a McKinley student who transfered out after a threatened Rachel was too much for her to contend with.
John Stamos' Dr. Carl Howell appeared in four episodes of the dramedy as a love interest for Emma -- and the denitist that gave Brittany and Santana laughing gas, paving the way for the duo's Britany Spears experience.
April and Will
Kristin Chenoweth's April Rhodes has popped up in three episodes of the show, playing an endearing alcoholic with the eyes for her childhood friend, Will Schuester. The boozy blonde eventually gifted McKinley with an auditorium when Sue Sylvester forced the glee club from its rehearsal space. Chenoweth, however, told THR that she thinks her "Glee days are over."
Idina Menzel plays Rachel's biological mother and the adoptive mother to Puck and Quinn's daughter, Beth. The former Vocal Adrenaline coach left the group to be closer to both Rachel and give Puck and Quinn the opportunity to get to know their daughter, arriving at McKinley and ultimately starting up the school's second glee club, the Trouble Tones.
Rapper Eve appeared as Grace Hitchens, coach of the Jane Addams Girls Chior in the "Hairography" episode in Season 1.
How I Met Your Mother's Neil Patrick Harrisappeared in an episode as Bryan Ryan, Will Schuester's former high school glee club nemesis.
Meet Brenda Castle
Molly Shannonappeared during Season 1, playing McKinley's astronomy teacher and badmitton coach who clashes almost upon arrival with Sue Sylvester.
Singer Josh Groban appeared in a few episodes as himself -- a guest judge at Regionals during the Season 1 finale "Journey to Regionals."
Katie Couric appeared on the post-Super Bowl episode of Glee, playing a reporter working on a story about Sue Sylvester.
Friend or Foe?
Jonathan Groff's Jesse St. James has recurred in a number of episodes, playing Rachel's boyfriend, a rival glee club performer-turned-New Directions member. Glee co-creator Ryan Murphy said in October that Groff would reprise his role as the coach of New Directions rival Vocal Adrenaline in Season 3.
Carol Burnett played Sue Sylvester's absent mother, the frequently referenced Nazi hunter Doris Sylvester. She joined Jane Lynch for a cover of "Ohio" from the musical Wonderful Town in the Season 2 "Furt" episode.
Dot Marie Jones earned a guest actress in a comedy Emmy nomination for her role as the tough-yet-tender Coach Shannon Beiste, who so far has been unlucky in love -- and on the football field.
Kathy Griffin, left, and Loretta Devineplayed judges at Regionals, with the former cast as a Sarah Palin type and the latter as a stripper-turned-nun.
Cheyenne Jackson has appeared in three episodes, as Dustin Goolsby, the aptly named coach of rival glee club Vocal Adrenaline.
Alias' Victor Garber guest starred as Will's father during the Season 1 "Acafellas" episode.
Father of the Year
Mike O'Malley picked up a guest star in a comedy nomination for his role as Burt Hummel, Kurt's incredibly supportive father.
Ricky Martin will guest star as a musically inclined Spanish teacher in a January episode that will likely feature the former General Hospital star performing in two big musical numbers.
Gloria Estefan will play Santana's mother during a Season 3 episode set to air in January.
Photo by: Adam Rose/FOX
New Coach on the Block
The Real Housewives of Atlanta's Nene Leakes guest stars as Roz Washington, Sam's swim team coach, in the Jan. 17 "Yes/No" episode.
Jeff Goldblum and Brian Stokes Mitchell played Rachel's gay dads and made their first appearance during the Valentine's Day episode.
Coach's Right-Hand Girl
Lauren Potter recurs as Becky, coach Sue Sylvester's go-to girl for anything and everything.
Guest Judge at Nationals
Lindsay Lohan will play herself in a Season 3 episode, appearing as a guest judge when New Directions heads to Nationals.
The Anderson Brothers
White Collar star Matt Bomer guest starred in an April episode, playing Cooper Anderson -- Blaine's older brother, who's treated as a local celebrity when he arrives at McKinley to offer New Directions some acting tips.
Ricky Martin guest starred as a Spanish teacher in an episdoe that featured an epic duet with Naya Rivera's Santana Lopez.
Former Melrose Place star Thomas Calabro will guest star as Puck's estranged father.