'The Glee Project' brings in Dianna Agron and Grant Gustin as mentors

"The Glee Project" Season 2 is certainly killing it on the guest mentor front. Nearly every big star from "Glee" has dropped by (or will drop by) at some point during the Oxygen reality show's run, and you can add two more names to that list: Dianna Agron and Season 3 villain Grant Gustin.

Agron will advise the reality contestants on "Actability" during the August 7 episode, which will focus on -- you guessed it -- acting challenges. Meanwhile, Gustin, who was discovered by casting director and "Glee Project" judge Robert Ulrich, will drop by on July 17 for "Theatricality." It's an appropriate theme, considering Gustin has a musical theater background and was performing on the national tour of "West Side Story" when he got the call for "Glee."

Amber Riley, Chris Colfer, Darren Criss and more will join Lea Michele, Cory Monteith, Naya Rivera and Jane Lynch as Season 2 mentors. Quite the star-studded cast these Season 2 contestants have seen!