Michael was the store manager of the Burbank Buy More throughout the series until Season Four, where he becomes assistant manager.
For the first two seasons he prefers to work, and especially deal with his subordinates, as little as possible. However, Big Mike is also frequently and closely involved with Morgan, Jeff and Lester in the store's plots, such as when the employees raid the Beverly Hills Buy More. When briefly deposed by Emmett as store manager, the other employees show a strong sense of continued loyalty to him.
He is an avid fisherman and frequently takes breaks during work to go fishing. He is demoted to a Green Shirt after Morgan and the other Buy More employees are tricked into making Emmett Milbarge look good in the eyes of Buy More corporate, but returns to being manager at the start of Season Three with a new, innovative view on how to manage the company and life, constantly referring to his inspirational financial school, El Guando.
Big Mike played college football as a linebacker, forming the "Defense of Death" with friend and teammate Jimmy Butterman (Jerome Bettis), and has inadvertently defeated two Fulcrum agents in season two, Leader and Ned Rhyerson.
He also has an affair with Harry Tang's wife (or fantasizes about her; unclear). Later, after Big Mike's wife divorces him, he begins dating Morgan's mother, Bolonia Grimes. Since then, he has taken Morgan under his wing as his de facto stepson and mentors his professional development.
For a brief period in 1988, Big Mike was a member of Earth, Wind and Fire, naming himself as "Rain." Although he failed at his own musical dream, his experiences led Lester to accept him as Jeffster!'s new manager. "Chuck Versus the Ring: Part 2" reveals that Big Mike is on a first-name basis with Buy More's founder, Moses. When Moses informs him that the Burbank branch is on the verge of closing, Mike holds a "going out of business" sale, courtesy of Lester's brilliant scheme. By the end of the episode, the store has been evacuated by Jeff. When Jeff and Lester suggest burning down the Buy More to collect the insurance, Big Mike wishes them good riddance, citing Lester's singing as torture and their antics such as answering phones that aren't ringing.
He returns again in Season Four. He comes back to inform Morgan about his intention to propose and marry his mother, Bolonia. He gives Morgan his ring (Full half carat cubic zirconium), and tells him to return the ring once he has the latter's permission. He also returns to Buy More and works as a Green Shirt, and tells Morgan that he is bursting with pride to see him as the new Store Manager. In Chuck Versus the Cubic Z, a game called Spy Attack is about to be released, and Buy More receives only 8 copies of the game for sale. While Morgan starts working on failsafe plans and attempts to fetch more copies of the game, he also claims that he can handle an angry mob, but can't handle a lifetime of calling Big Mike "dad". Much to his dismay, he fails to get more copies of the game or to control the angry mob. A riot breaks out, during which, he loses Big Mike's ring. However, Michael saves the day by successfully taming the crowd, showing his capabilities in terms of crowd control and leadership, which encourages Morgan to promote Big Mike to the position of Assistant Manager. On the other hand, Morgan is unable to find Big Mike's ring. Michael does not blame Morgan or hold it against him, but rather forgives him, and gives him a hug. Morgan also gives him the permission to marry Bolonia.
In "Chuck Versus the Muuurder", Big Mike uses the BM costume (which is the Buy More logo, not to be confused with his nickname). He was then kidnapped and held in a Large Mart cage. This was done due to Jeff and Lester previously kidnapping their mascot, Kevin Bacon. At the end of the episode, the pig was returned to Morgan just as Big Mike returned. Large Mart then lights up the BM costume on their door step anyway even though they have already found Kevin Bacon for them.
Since the pilot episode, Big Mike is seen only as a typical boss at a mall, serving as a man who would angrily handle his staff for either not doing the job properly, or not doing the job as much as possible. Mike would even host competitions among his staff, lying to them that they would receive extraordinary prizes such as a new iPhone, and that whoever loses in having the most sales, would be fired - also another lie.
As of the later half of Season Two, Big Mike has shown to be more understanding and respecting of his employees. This change of his character may have been the cause of Big Mike meeting his new love and Morgan's mother, Bolonia Grimes. He was always seen as strict, angry, and selfish through the series until meeting her.
Throughout Season Three, Mike even goes as far as to offer himself as the manager for Jeffster!, although quits when Jeff and Lester have caused him a deep amount of trouble in the season three finale. It is assumed that he still is no longer the manager for Jeffster! throughout the fourth season.
In the beginning of Season Four, Big Mike has been given the assistant manager position, with Morgan serving as the new store manager. Mike had been trying to propose to Bolonia, and had asked Morgan's permission for his hand in marriage with her. By Season Five they are married.
- Chuck's mother is portrayed by Linda Hamilton, and both Mark Christopher Lawrence and Hamilton have played in Terminator 2. Mark was cast as a guard at a hospital for the criminally insane, where Sarah Connor was being held at.
- Over the course of the series Big Mike has unintentionally stopped 2 major criminals from escaping. He stopped Leader in season 2 and Hugo Panzer in season 4.
- Despite being informed by Jeff and Lester that Chuck is a spy in the final episode of the final series, he chooses not to believe it. This makes him the only major character in the show to not know of Chuck's spy business.
- Big Mike is often involved in the Subway promo segment of later season episodes.
Anna Wu • Alex McHugh • Alexei Volkoff • Bryce Larkin • Carina Miller • Clara Woodcomb • Clyde Decker • Daniel Shaw • Diane Beckman • Emmett Milbarge • Gertrude Verbanski • Hannah • Harry Tang • Jane Bentley • Jill Roberts • Langston Graham • Mary Bartowski • Nicholas Quinn • Stephen Bartowski • Vivian Volkoff