The highly anticipated "Glee" 100th episode is just a few months away, and spoilers confirm that ALL cast members have been invited back to participate in the season episode!

As fans may now, the "Glee" 100th episode will be airing on March 18 of next year, and as the fall finale looms closer, executive producer Ryan Murphy has set Twitter on fire with the wonderful news.

But, despite all the former "Glee" cast members being invited back for the 100th episode, it doesn't necessarily mean all of them CAN be back due to scheduling.

So who are the confirmed returning "Glee" cast members for the 100th episode?

According to spoilers by E! Online, recent "Dancing With the Stars" winner Amber Riley is set to reprise her role as Mercedes Jones.

Joining Mercedes will be Noah Puckerman, portrayed by Mark Salling.

But, one cast member everyone is wondering about is Dianna Agron, who was conspicuously absent from the "Glee" Cory Monteith tribute episode.

"She is still very much a part of the 'Glee' family and always welcome," said an insider source.

Although an official confirmation has not been made about Dianna Agron's return for the 100th episode, TVLine believes it will most likely happen unless scheduling gets in the way.

"I hear she wants to do it. Whether the dates work out is another question," writes Michael Ausiello.

So, if "Glee" brings back all the former cast members, who will you be most excited to see?