Some accomplished gentlemen will be appearing on The Big Bang Theory as its final season continues. Big Bang production studio Warner Bros. revealed Wednesday that Harold and Kumar Go to White Castle star Kal Penn and Lord of the Rings veteran Sean Astin will guest star in an upcoming episode.

They'll play Dr. Campbell (Penn) and Dr. Pemberton (Astin), a pair of physicists who who accidentally confirm Sheldon (Jim Parsons) and Amy's (Mayim Bialik) super-asymmetry theory. Sheldon and Amy thought the theory they developed together was disproven until they had a breakthrough thanks to an assist from Sheldon's dad (Lance Barber) via VHS tape.

Penn joins a long list of smarty-pants Big Bang Theory guest stars. The House and Designated Survivor star took a break from acting from 2009 to 2011 to work in the Obama administration as an Associate Director of the White House Office of Public Engagement focusing on youth outreach.

Astin is a quiet icon who's appeared in classic movies like The Goonies, Rudy and The Lord of the Rings franchise. More recently, he starred on Season 2 of Stranger Things as the ill-fated Bob.

The Big Bang Theory is in the midst of its 12th and final season. Other upcoming guest stars will include Brian Thomas Smith and Lindsey Kraft.

The Big Bang Theory airs Thursdays at 8/7c on CBS.

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Kal Penn, Sean AstinKal Penn, Sean Astin