Before he was first seen, Bernadette warned Howard not to mention Jimmy Carter, gardeners, foreigners, homosexuals, Sean Penn, Vatican II, organic food, designated hitter rule, gun control, recycling, or Howard's Jewish heritage, indicating that he is far-right-wing.
Overall, Mike is a hardened and retired 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 at first, but that later grew after Howard became an astronaut and married his daughter. 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."
In "The Fish Guts Displacement," Howard and Bernadette are having dinner with 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 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 (Mike 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. Mike, along with everyone else except Bernadette, laughed when Raj brought up Howard throwing up in zero gravity and his vomit went right back into his mouth, a cycle which repeated constantly.
In "The Spock Resonance", Mike is brought to the Wolowitz House by Bernadette to start construction when she wants to start redecorating. A very funny scene with Mike and Howard happens under the house - Mike wants to know why Howard doesn't want kids. Howard denies that. Bernadette hears their conversation under the floor and starts trying to make an earthquake and aftershocks so that they'll stop talking. Last scene with them reveals that his wife raised the kids while all he did was come home from work, sit on the couch and drink beer and also Howard and Bernadette's conversation after Mike leaves sounds like they are seriously considering a baby.
- Mother or Mother-in-law: Unnamed
- Wife: Mrs. Rostenkowski
- Daughter: Bernadette Rostenkowski
- Son: Joey Rostenkowski
- Children: Four other unnamed children
- Son-in-law: Howard Wolowitz
- Grandchildren: Unnamed
- Granddaughter: Halley Wolowitz
- Grandson: Neil Michael Wolowitz
|The Big Bang Theory Episodes|
|Young Sheldon Episodes|
|Appeared||M = Mentioned||Did not appear||Not aired/Not available|
|V = Voiced||C = Cameo||F = Flashback||I = Indirectly mentioned||P = Pictured|
- He is one of five fathers of every main character who has physically appeared on the show; the others being Raj's father V.M. Koothrappali, Penny's father Wyatt, Leonard's father Alfred Hofstadter and Amy's father Larry Fowler (Sheldon's father is dead, Howard's left him at age 11, Stuart's is only mentioned, Leslie's hasn't been seen or mentioned and Emily's is only mentioned and possibly dead).
- It is implied that he and his wife got married in 1978.
- In "The Septum Deviation", it's revealed that he and his wife barely speak to each other, but is obviously devoted to her since in "The Fish Guts Displacement" (S6E10) Mike was being defensive since Howard said that he and Mike are married to a couple of ball-busters and he replies "That's my wife and daughter you're talking about".
- According to Bernadette, whenever he would come home from work, he would just sit on the couch and drink beer.
- In "The Neonatal Nomenclature", Bernadette reveals he is dying, implying that he might die in a future episode. If he does, then he would be the third parent of a main character that is dead, after Sheldon's father George Cooper Sr. and Howard's mother Debbie Wolowitz.
- In spite of his age, Mike is still physically strong, as evidenced in the series finale when Leonard mentioned that Mike cracked one of Stuart's ribs while hugging him.