Lindsay Lohan
The troubled actress - who has previously complained about the musical TV series for mocking her stints in rehab - is reportedly in final negotiations to appear on the programme to play herself as one of the celebrity judges in the annual nationals competition, website TVLine reports.

Meanwhile, Whoopi Goldberg has signed on for a stint in the show that is expected to last for three episodes.

The 'Sister Act' star will play Carmen Tibideaux, a professor at New York Academy of the Dramatic Arts (NYADA), the school which graduating students Rachel Berry (Lea Michele) and Kurt Hummel (Chris Colfer) have applied to.

Whoopi's character - who will first appear on US screens on May 1 - is expected to oversee the pair through their auditions.

Although Whoopi is only slated to appear this season, it is possible she may return in the future as Lea and Chris' characters will remain with the show next year, despite graduating from William McKinley High.

Fox Entertainment president Kevin Reilly said recently: "People are going to graduate, and their story lines will carry on through graduation into Season 4, also keeping the William McKinley High School paradigm intact and building in elements of characters who have graduated.

"It's a very cool way they've figured out how to do that."