December 04, 2013 11:15am PT by Lesley Goldberg
'Glee's' 100th Episode: Dianna Agron, Heather Morris Among Original Stars Returning
Glee's 100th episode is shaping up to be a special one.
In addition to letting fans pick 10 of the show's most beloved performances for a remix treatment, co-creator Ryan Murphy has extended the option to return to all of the show's original castmembers.
Murphy noted "all" of the Glee "originals" were invited to return for the March 18 episode and has confirmed several of the former series regulars have committed to coming back to the Fox musical.
Confirmed to return so far, per Murphy's Twitter feed, are: Heather Morris (Brittany), Harry Shum Jr. (Mike), Mark Salling (Puck), newly minted Dancing With the Stars winner Amber Riley (Mercedes), Dianna Agron (Quinn) and Kristin Chenoweth (April), the latter of whom won an Emmy for her guest turn.
Of those already announced, Morris' return is the most notable as the actress behind the lovable former Cheerio has not appeared since Glee's fourth-season finale when Brittany was written out of the series and bound for early admission at MIT. At the time, her future with the series was unclear and she did not have a deal to return. Since her exit, Morris has given birth to her first child, a baby boy named Elijah who was born in September.
Agron's return is the biggest of the bunch. The actress has not appeared since the 14th episode of Glee's fourth season and was not a part of season five's tribute to late star Cory Monteith. That episode -- "The Quarterback" -- also featured numerous original stars returning to pay their respects to Monteith and Finn Hudson.
Morris, Salling, Riley and Shum were all downgraded from series regular status in June but the quartet -- along with Agron and Jayma Mays -- were considered likely to return for guest appearances on the musical dramedy.
Glee's freshman season had 12 stars who received top billing, including Mays (Emma) -- who now stars on CBS' The Millers but has appeared sporadically in season five -- as well as Jessalyn Gilsig (Terri).
Set to air March 18 at 8 p.m., the top 10 fan-selected Glee songs will be remixed and performed by the current members of New Directions as the hour focuses on McKinley High's latest crop of seniors as they march toward graduation and reminisce about their most memorable moments.
Glee airs Thursdays at 9 p.m. through Dec. 5, then takes a break before returning to Tuesdays at 8 p.m. in February.