Police officer, retired
Mike Rostenkowski is a retired police officer and the father of Bernadette Maryann Rostenkowski-Wolowitz, as well as several younger children and the father-in-law of Howard Wolowitz. His first appearance was in "The Launch Acceleration." He is portrayed by actor Casey Sander.
Before he was first seen, Bernadette warned Howard not to mention Jimmy Carter, gardeners, foreigners, homosexuals, Sean Penn, Vatican II, organic food, gun control, recycling, or Howard's Jewish heritage, indicating that he is far-right-wing.
Overall, Mr. Rostenkowski is a hardened police officer, who has a rough and rude personality, and often bullies others. He admitted to Howard that he does not like him, but is impressed with him being an astronaut. He appears to have a soft spot for Bernadette, calling her his "little girl." He has called Howard's mother a "piece of work" and pointed out that she had an even bigger mustache than him. He mentioned that his former partner was shot and killed by his partner's insane wife.
He doesn't seem to care about Howard, despite the fact that he's Mr. Rostenkowski's son-in-law. His respect for Howard grew, however, when he learned Howard had been selected to become an astronaut. When Howard told him of his terror of going to space, Mr. Rostenkowski said "It's gonna be okay, son. A pretty girl like Bernadette... She'll find a new guy."
He appears to be incredibly strong, since he was seen cracking walnuts with his bare hands in "The Launch Acceleration."
In "The Fish Guts Displacement," Howard and Bernadette are having dinner at her parents. Howard and Mike get pushed into a fishing weekend by their spouses and it turns out neither of them want to go. Mike suggests that they go to a casino to shoot craps. They bond somewhat and he tells Howard to call him Mike and no longer "Sir". In this episode, he reveals that he likes to use big shells while duck hunting so that they explode: " you can't eat them afterwards, but it's fun watching them blow up."
In "The Thanksgiving Decoupling," his wife is out of town and Bernadette gets him to come to Howard's mother's house for Thanksgiving dinner though he would rather watch football at home. Since Sheldon knew football thanks to his father and had lost his father, Mike and Sheldon Cooper bond and get drunk together.
In "The Table Polarization," he, Bernadette, Raj and Mike Massimino (via web chat) perform an intervention on Howard's decision to go back to space (he had to be prodded by Bernadette to agree about loving him). He mentioned that Howard asked him to shoot him in the foot, at which Howard insisted was a joke.
- He is one of the three fathers of the main characters who have physically appeared on the show; the others being Raj's father V.M. Koothrappali and Penny's father Wyatt. (Leonard's father is only mentioned, Sheldon's is dead, Howard's left him at 11, Amy's has never been seen or mentioned and Stuart's is only mentioned).