Bernadette Rostenkowski

Bernadette Rostenkowski, later Rostenkowski-Wolowitz, is played by Melissa Rauch, recurring in season three and starring from seasons four to twelve. She is introduced as Penny's co-worker at The Cheesecake Factory, waiting tables to pay for graduate school in microbiology, and begins dating Howard; she was one of the supporting characters promoted to the main cast alongside Amy Farrah Fowler and Stuart Bloom. Howard and Bernadette marry in the fifth-season finale, a wedding moved up when NASA brought forward Howard's space mission, and in season nine they learn they are expecting a baby. By season five she, Penny and Amy have become a close trio who are often seen together.