In the course of the serie, it is shown the dificulty leading men to interact with people outside their environmen, mainly female, leading to funny situations.
- Dr. Sheldon Lee Cooper, a theoretical physicist. He is completely incapable of lying and keeping secrets. He is logical of all the situations happening around him forces him to draw conclusions strictly scientificand therefore do not agree with the lies. It is completely chaste and has no interest in sex. It is usually dressed in a sweater over a shirt with logos of superheroes.
- Dr. Leonard Leakey Hofstadter, an experimental physicist. He obtained his doctorateat at the age of 24. While much more sociable than Sheldon, like Rajesh and Howard, has never had success with women, although of the four is the only one who has had stable girlfriends throughout the chapters of the series, including Sheldon's nemesis, Leslie Winkle.
- Mr. Howard Wolowitz Joel, an aerospace engineer, has worked on a secret projectof NASA waste disposal, or as his teammates call "a space vater." It looks old-fashioned Jew of his time: always wears tight clothes and psychedelic, it is alsoallergic to peanuts. His best friend is Raj and still lives with his mother, although healways says "my mother lives with me."
- Dr. Rajesh Ramayan Koothrappali, an astrophysicist. This character represents the stereotype of an Indian living in America. His family is rich and who would havefewer problems in the group if it were not suffering from a rare disorder (selective mutism) preventing him from talking with women except his mother and sister, orwith effeminate men in appearance, only communicates with them if you are drunk(or think you might).
- Penny, a waitress and aspiring actress. She is a friend of the four only by accidentwhen Sheldon and Leonard's neighbor and during the first few seasons is the only friend of the opposite sex of the group. It is a waitress at the restaurant "The cheesecake factory". It was Leonard's crush during the first few seasons, until they started an affair desired in the third season.
Manuel Pérez Fernández