Mary Cooper

Mary Cooper is Sheldon Cooper's mother, a devout Christian from Texas. She has two other children, Sheldon's fraternal twin sister, Missy, and an older son named George Jr.. Mary herself is not intellectual like her son, but is very wise; she appears to be an extremely good mother and is the only one who has ever been able to control Sheldon; Leonard described her as Sheldon's "Kryptonite" because he always succumbs to her.

She is called upon by both Leonard and Penny when Sheldon gets particularly difficult to handle. In particular, she was brought in to address:
 * Sheldon picking up random projects to consume his time after being fired. Mary initially tried to put him into a comfort zone in which he would be receptive to trying to get his job back and, when tired of waiting, forced Sheldon to apologize to Dr. Gablehauser.
 * Sheldon getting into a protracted dispute with Penny. After seeing the battle escalate several times, Leonard advised Penny to call Mary and Mary responded by ordering Sheldon to forgive and apologize to Penny.
 * Sheldon sinking into a depression after discovering his research data on the Arctic Expedition was faked. After Sheldon fled to her home in Texas, Mary convinced Leonard, Raj, and Howard to come to Texas and apologize and further convinced Sheldon to forgive them by calling evolution an "opinion".
 * Sheldon "sulking" after "breaking up" with Amy Farrah Fowler (including the purchase of 25 cats). After meeting with Amy, Mary uses reverse psychology to trick Sheldon into getting back together with Amy.

Sheldon describes Mary as being a "kind, loving, religiously fanatical, right-wing Texan, with a slightly out of scale head and a mild Dr Pepper addiction.

Sheldon has claimed that he is not crazy because his Mother had him tested. Mary Cooper said that she wished she had him tested again.

Trivia
Laurie Metcalf was a regular in the sitcom Roseanne , along with Johnny Galecki and Sara Gilbert.