Gustin, whose credits include the national tour of West Side Story, plays Dalton Academy Warbler Sebastian on the FOX series and will take part in the July 17 episode of the Oxygen competition. Agron, who plays Quinn, is slated to appear on the August 7 episode of the series.

As previously reported, other guest mentors on The Glee Project this season are Chris Colfer, Darren Criss, Samuel Larsen, Jane Lynch, Lea Michele, Cory Monteith, Amber Riley, and Naya Rivera.

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