Yes, that's Keith Carradine on The Big Bang Theory. He's played the character of Penny's dad.
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Leonard tries to keep an affair secret from Sheldon on "The Irish Pub Formulation." This is a scene from that episode.
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A flashback to when Leonard first moved in with Sheldon and they signed the roommate agreement.
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Before there was Leonard, there was an even angrier roommate. Angry enough to write "Die Sheldon Die."
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A flashback to the nerds when they first met playing Gamecube together.
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Sara Gilbert is seen here on The Big Bang Theory. She plays the character of Leslie.
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Penny and Leonard come outside to see Sheldon trapped by a net from the security system they installed.
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As usual, Leonard and Penny get into an argument. This time? About psychics.
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Sheldon helps decorate the tree and wants to add the bust of Sir Isaac Newton, which he argues is more Christmasy than Jesus.
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After years of trying to get his mother's affection, Leonard finally gets a hug from Beverly (Christine Baranski). All it took was getting her drunk.
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Bernadette (Melissa Rauch) joins the guys for lunch at work as she begins to bond with Leonard over his work.
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Wolowitz confronts Leonard when he gets jealous over his friend bonding with his girlfriend, Bernadette.
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TBBT Quotes

I just gave you my virginity, woman. Cool your jets!

Sheldon

(Singing) Thor and Dr Jones, Thor and Dr. Jones. One plays with lightening, the other plays with bones.

Howard and Raj