Bernadette Maryann Rostenkowski-Wolowitz is a microbiologist who is married to Howard Wolowitz. Although Bernadette is generally nice and good-natured, she has shown a dark side and admits she is a very vengeful person. When Bernadette is angry, she sounds a lot like Howard's mother.
Howard was introduced to Bernadette by Penny, who was a waitress with her at the Cheesecake Factory. Howard and Bernadette soon bonded over their overbearing mothers. When Howard realized this could become a lasting relationship, he impromptly proposed to Bernadette. She did not accept the proposal, but the pair continued to date any way.
Towards the end of Season 3, Bernadette abruptly broke things off with Howard. It was later revealed she dumped Howard after catching him having cyber sex with "Glacinda the Troll" on World of Warcraft. Howard and Bernadette got back together early in Season 4. Howard proposed to Bernadette near the end of Season 4 and this time she accepted.
After gaining her PhD in micro-biology, Bernadette was head-hunted by a big pharmaceutical company and offered a well paying job. Bernadette earning more than Howard has occasionally caused a rift in their relationship. Howard's desire to start a family has as times created tension in their marriage as Bernadette does not like children and doesn't want to put her career on hold.
When Wil Wheaton uploaded a video from Howard's bachelor party of Raj drunkenly describing some of Howard's sexual conquests, Bernadette questioned their impending wedding. A heart-felt apology from Howard for his past behavior won Bernadette over.
Although she was intitially against Howard becoming an astronaut, Bernadette eventually supported her husband in his dream to go to space. As Howard's space mission approached, Bernadette decided that they should get married before he goes into space. After the couple were unable to wed at City Hall, they agreed to marry on the roof of the guys' apartment as the Google Earth satellite passed above. Sheldon, Leonard, Penny, Raj and Amy became ministers and performed the wedding.
Bernadette supported her husband Howard while he was in space and, when he returned and wouldn't shut up about it, helped him adjust back to civilian life. As a married couple, Howard's attachment to his mother and living in her house angered Bernadette, who wanted him to move into her apartment permanently. When she finally convinced Howard to move his stuff away from his mother's house, his sentimental story of how he helped his mother through her husband leaving her gave Bernadette second thoughts.
Stuart: Oh, so she's good enough for Howard but not for me?
Bernadette: Yeah. Go have weird relationships with your own mother and cousin. This is his turf.
Penny: That, believe it or not, is my prom dress.
Bernadette: Wow, you still have it? I just assumed it was balled up in a corner of a barn somewhere.
Bernadette: Are you okay?
Raj: No, I'm not okay. I feel like I'm going to jump out of my skin.
Bernadette: I told you not to wax down there. It's itchy when it grows back.
Bernadette: Aww, Raj did the dishes.
Howard: How do you know I didn't do them?
Bernadette: Because once when all the knives were dirty, you cut a bagel with your keys.
Leonard: You don't go to into science for the money.
Bernadette: Speak for yourself. Last month my company both invented and cured restless eye syndrome. Ka-ching, ya blinky chumps!