Mac (real name Ronald McDonald) is a co-owner of Paddy's Pub and generally the pub's most active manager. He is roommates with his best friend from high school, Dennis Reynolds, and has been best friends with Charlie Kelly since childhood. Mac is a member of The Gang which also includes Dee and Frank.
Mac gets upset at injustices, but will pounce on any opportunity he sees as a fair chance to bang or make money. He is proud of his body and is currently in denial about his weight gain.
Mac is portrayed by Rob McElhenney.
- Mac comes from a broken home; his father Luther was an incarcerated meth dealer, and his mother was extremely apathetic.
- Mac constantly seeks the acceptance of others, especially his parents, but his over-earnest efforts make him come off as an asshole. ("Dennis Looks Like a Registered Sex Offender")
- Mac is jealous of other people's success.
- Mac is highly competitive, and is unable to control his competitiveness. ("The Gang Gets Extreme: Home Makeover Edition")
- When he learned that Charlie and the McPoyle brothers were possibly sexually molested by their—and Mac's—elementary school gym teacher, he feels rejected and worries that he is somehow inferior for having not been molested himself. He proceeds to research why he didn't get molested, stating that, "If the McPoyles got blown, and Charlie got blown, then why didn't I get blown?" ("Charlie Got Molested")
- Although he seeks his friends' acceptance, Mac takes special pleasure in undermining, physically harming, contradicting, and publicly belittling Sweet Dee at every possible opportunity.
- Like Dennis, Mac sees himself as superior to the rest of The Gang and often attempts to prove his supremacy. For instance, in an attempt to impress Charlie and Dennis, he makes a series of "Project Badass" videotapes that consist of various idiotic stunts; however, the pair believes that Mac is just trying to "bang" them. ("Mac's Banging the Waitress")
- Mac is Catholic and the only member of the group to profess a religious faith. ("The Gang Exploits A Miracle") However, this has done little to affect his general lack of ethics.
- Mac is easily flattered and manipulated, especially if complimented about his body or his fighting skills. He has an ongoing sexual relationship with a pre-op transsexual named Carmen, largely because she was so adept at flattering him about his buff body. ("Charlie Has Cancer") He claims that he is just "putting in time" as he waits for her surgery. ("Mac Is a Serial Killer")
- Mac prefers not to use condoms, even when he's having sex with people he doesn't know. ("Mac Is a Serial Killer") He only reluctantly agrees to wear a condom with the Waitress in "Mac's Banging the Waitress" There is much evidence that Mac is harboring one or more STDs.
- Mac seems to have a thing for older women. He had sex with Dennis and Dee's mom, Barbara Reynolds, later saying it was the best sex of his life. ("Mac Bangs Dennis' Mom") He also expressed interest in Barbara's sister, Aunt Donna. ("The Gang Gives Frank an Intervention")
- Mac places sex above friendship, and has betrayed his two best friends by dating or having sex with women very important to them:
- In high school, Mac had sex with Dennis' prom date and blamed it on Tim Murphy. ("The High School Reunion, Part 2: The Gang's Revenge")
- Later, Mac started secretly dating the Waitress despite Charlie's obsession with her. ("Mac's Banging the Waitress")
- Mac frequently strives to appear "hard," usually to impress his father or friends. In reality though, he is a coward.