Season 6

Season 6 '''premiered on September 27th, 2012, and ended on May 16, 2013. All of the seven regular actors on the show returned to their respective roles. The first episode taping began on August 14, 2012. It was announced that starting from this season, Kevin Sussman, who plays Stuart Bloom, was promoted as the eighth series regular, though he doesn't appear in every episode.'''

Cast

 * Sheldon Cooper, Ph.D., portrayed by Jim Parsons, is a theoretical physicist. Originally from Galveston, Texas, he was a child prodigy, starting college at the age of 11, right after completing the fifth grade, and received his first Ph.D. at 16. He has an IQ of 187 and an adherence to routine; a lack of understanding of irony, sarcasm, and humor; and a complete lack of humility or basic empathy. He is currently dating Amy Farrah Fowler and considers her to be his "girlfriend" as outlined in his Relationship Agreement with her. Sheldon gradually moves into a more comfortable and intimate relationship with Amy without any true romantic intimacy. He admitted to being very fond of her and that someday they might be intimate in "The Cooper/Kripke Inversion" and "The Love Spell Potential".
 * Leonard Hofstadter, Ph.D., portrayed by Johnny Galecki is an experimental physicist with an IQ of 173 who received his Ph.D when he was 24 years old. He shares an apartment with colleague and friend, Sheldon Cooper. He and Penny dated at one point during the series, but they have since broken up. He dated Raj's sister, Priya for half of the fourth season, and a short period of the fifth season. He and Penny got back together in "The Beta Test Initiation", although the relationship will be treated like a Beta Test, where bug reports will be presented when necessary. As their relationship becomes more stable, he proposes to Penny on multiple occasions. After she accidentally tells him that she loves him in "The 43 Peculiarity", he asks her to propose to him when she is ready in "The Tangible Affection Proof".
 * Penny, portrayed by Kaley Cuoco, is the attractive, blonde neighbor who lives across the hall from Sheldon and Leonard. Penny is from Omaha, Nebraska. She has aspirations to a career in show business, and has been to casting calls and auditions but has not been successful thus far. To pay the bills, she works as a waitress at The Cheesecake Factory. Her last name has never been revealed. She and Leonard dated throughout most of Season 3, but they have since broken up. In "The Beta Test Initiation", she and Leonard got back together, although this time around, they are taking their relationship slowly, and treating it like a Beta Test and present each other bug reports when necessary until Leonard asks her to marry him. Penny explores her feelings for Leonard and finally tells her she loves him in "The 43 Peculiarity". After multiple marriage proposals from Leonard, she agrees to propose to him when she was ready in "The Tangible Affection Proof".
 * Howard Wolowitz, M.Eng., portrayed by Simon Helberg, works as an aerospace engineer. He is Jewish and lives with his mother. Unlike Sheldon, Leonard, and Raj, Howard lacks a Ph.D. He defends this by pointing out that he has a master's degree in Engineering from the Massachusetts Institute of Technology and the apparatus he designs are actually built and launched into space, unlike the purely abstract work of his friends. He provides outrageous pick-up lines and fancies himself a ladies' man with suitably unimpressed reactions from Penny. Though he finds that he has limited success with other women at first, he begins dating Bernadette in season 3, but they break up; they get back together in the Season 4 episode "The Hot Troll Deviation", become engaged in the episode "The Herb Garden Germination", and married on the final episode of season 5, "The Countdown Reflection". After spending weeks at the International Space Station, Howard returns, moves out of his mother's house and with the help of his wife starts to grow up.
 * Rajesh Koothrappali, Ph.D., portrayed by Kunal Nayyar, originally comes from New Delhi, India. He is an astrophysicist. Known commonly as "Raj", he works alongside Sheldon exploring the string theory implications of gamma rays from dark matter annihilation. He is very shy around women and is physically unable to talk to them unless he drinks alcohol. He has much better luck with women as opposed to his overly confident best friend Howard. His sister, Priya, dated Leonard. During season 6, he was seeing a woman, Lucy, who had more psychological problems than him. After she dumps him, he finds that he can finally talk to women.
 * Bernadette Rostenkowski Wolowitz, Ph.D., portrayed by Melissa Rauch, is a former waitress and co-worker of Penny paying her way through graduate school microbiology studies. Bernadette is introduced to Howard by Penny. At first she and Howard did not get along, as they appeared to have nothing in common. When they found out that they both have overbearing mothers, they feel a connection. She was upgraded to main cast status in the episode "The Hot Troll Deviation", in which she and Howard revisit their previously unsuccessful relationship. They got engaged in Season 4's "The Herb Garden Germination" and married on the final episode of season 5, "The Countdown Reflection". Since earning her doctorate, Bernadette is now finally a microbiologist, and earns more than her husband. After getting Howard to move out of his mother's house into her apartment, she continues to push him to grow up.
 * Amy Farrah Fowler, Ph.D., portrayed by Mayim Bialik, is a woman Raj and Howard met on an online dating site using a faux account for Sheldon. She is essentially the female duplicate of Sheldon and she and Sheldon become friends although, as Sheldon claims, she is a girl and is his friend, but she is not his girlfriend; however, since the "The Flaming Spittoon Acquisition", she is officially Sheldon's girlfriend. She and Sheldon continue to explore relationship intimacy without any romantic intimacy. Amy is a neurobiologist and is more inclined to explore human relationships than Sheldon partly due to Penny's friendship. Amy is from Glendale.
 * Stuart Bloom, portrayed by Kevin Sussman, is the owner of a comic book store to which the gang frequently goes. He is also a nerd, but he has a talent for drawing, is a graduate of the Rhode Island School of Design, and possesses a few more social skills than they do. Stuart starts hanging out with the gang as a replacement for Howard, as long as he acts like Howard as stipulated by Sheldon. He and Raj have become good friends, with a broke Stuart staying at Raj's place and having most of his expenses covered by him, in a relationship that strongly mirrors the Raj-Howard pairing before Howard met Bernadette — including the fact that Raj and Stuart appear to others as acting like a same-sex couple while both men are straight and Raj is unaware of how they are coming across. Stuart notices it from time to time.

Storyline
The show's co-creators, executive producers, and writers, Chuck Lorre, Bill Prady, and Steven Molaro revealed some plot points for the sixth season, with Molaro revealing that the gang will have to deal with some very adult themes. Some of the plot points; however, did not take place during this season (see below "did not take place") and may have been delayed to Season 7.
 * Mrs Rostenkowski, Bernadette's mother, will be introduced.
 * Leonard and Penny will continue to have issues in their relationship, regarding the contradictions of what they want out of the relationship. They will still each be at different places in their relationship.
 * Raj will struggle being the only single guy in the group, especially since Howard is married.
 * Sheldon will essentially remain the same, regardless of how his relationship with Amy progresses.
 * Mary Cooper (Sheldon's mother) and Dr. Beverly Hofstadter (Leonard's mother) will meet, causing a mother envy. [Did not take place]
 * Mary Cooper may meet Amy's mother as well, although it will just be mentioned by Sheldon and Amy, and not be shown on the show. [Did not take place]
 * Raj's love life will be further explored.
 * There is not going to be any wedding in the season.
 * Sheldon will continue to be pushed by Amy regarding the progress in their relationship (she has a five-year plan to keep pushing him forward toward marriage).
 * Penny will continue to lean on Amy and Bernadette as she matures and seeks deeper meaning from her relationship with Leonard. An outside force could also factor in to the relationship.
 * Penny is going to get an acting job when a USC student named Cole offers her to star in a student film. Cole will appear in the eighth episode of the season.
 * Another major guest star could appear.
 * Howard will struggle while he is in space and once he returns, due to the need to readjust himself back into normal society after being away.
 * Bernadette will have to deal with a husband who is full of himself once he returns from the International Space Station.

Mayim Bialik's Accident
On August 15, 2012, around midday (the day after the taping of the first episode), Mayim was involved in an accident when the white Volvo she was driving was hit by a car making a sudden left turn. Mayim's right hand was reported to be seriously injured and not long after rumors were surfacing that she might even lose her fingers. Mayim took to her Twitter (via her husband) that despite being in pain, she will keep all her fingers. She added that her right hand; however, is very impaired, and since she will have a long recovery, her assistant, Brandon, will help her type her blogs. Following that, it was reported that her injury will not disrupt the production of the show, and this was confirmed by Bill Prady on his Twitter that Mayim will make it to the next episode rehearsal with "all her ten fingers". Mayim later blogged that she will not be taking any week off from the show. It is now confirmed that, much like Kaley Cuoco's broken leg during the filming of Season 4, her injury will not be written into the show, and will be hidden, as the second episode of the season 6 was taped without including her injury as part of the storyline.