Parsons is best-known for playing Sheldon on the hit series "The Big Bang Theory," a role for which he's picked up three Emmys and a Golden Globe. It will be his first "SNL" appearance.
Meanwhile, Beck will be making his seventh appearance as musical guest. He first performed on the show way back in 1997.
The episode will also mark the debut of Colin Jost as Cecily Strong's co-anchor on "Weekend Update," following the departure of Seth Meyers.
In addition to "Theory," Parsons will soon be seen alongside Zach Braff and Kate Hudson in "Wish I Was Here," directed by Braff ("Garden State").
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