Mac (It's Always Sunny in Philadelphia)

Mac is a co-owner and self-proclaimed bodyguard or "sheriff" of Paddy's, and is generally the pub's most active manager. Mac is played by Rob McElhenney.

Mac frequently uses his signature line, "What's up, bitches?" throughout the series. In many episodes, Mac will enter the bar announcing "I've got news" or a variation of the phrase, to set the episode's plot in motion. The others rarely share his enthusiasm, but he usually convinces one of them to follow him, though often reluctantly. Throughout the series, Mac uses a "puppy-dog look" when he is ashamed or when he proposes something reprehensibly shameful.

For the first six seasons, Mac's full name was not revealed, though in the season four episode "Mac & Charlie Die," Mac's father's name is listed as "Luther Mac" on his parole papers and his mother is referred to as Mrs. Mac. In the episode "Who Got Dee Pregnant?," one of the McPoyle brothers refers to Mac as "Macwell." In the episode "The Gang Cracks the Liberty Bell" Mac, or at least Mac's 18th Century counterpart, is called "McDonald," suggesting that this is his surname. Mac's full real name, Ronald McDonald, is revealed in the season seven episode "The High School Reunion". Mac hates the name due to its connection with the mascot of McDonald's as well as his old nickname, "Ronnie the Rat," which he obtained from ratting on his peers in high school. He prefers to be simply called "Mac".

Mac comes from a broken home; his father has been incarcerated for dealing meth and his mother is extremely apathetic and unemotional. He is very deep in denial of the fact that his parents do not love him and he constantly denies the fact that he may have had a rough childhood, despite the contrary being obviously true (for example at Christmas his family would break into other peoples' houses and steal their presents, which he insists to be a Philadelphia tradition). He describes himself as a karate expert and total "badass". Mac constantly seeks the acceptance of others, especially his parents, but his over-earnest efforts do not endear him to others. Earlier, under the impression that his father would possibly murder him after being paroled, Mac later receives a warm letter from his father, specifically requesting that Mac stay away from him. This letter is written as Mac's father fears that Mac's destructive tendencies could harm him. Dennis notes that the only reason Mac hung out with the popular kids in high school was because he sold them all weed and even then was considered an "asshole."

Mac is considered by every member of The Gang to be a "jerk" and is nearly always the first to start betraying the others. He has repeatedly shown his misogynistic views, believing himself to be superior to women and even stating that he outright "hates" women. Mac sincerely believes that he is an adept martial artist with "cat-like reflexes" and usually wears sleeveless shirts to draw attention to his physique and exhibit his tribal tattoos. Despite his enthusiasm towards karate, he is shown to have no real skills in the sport.

Like Dennis, Mac frequently asserts 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 set to music. However, while Dennis' hubris seems to be rooted in narcissism, Mac's overconfidence is implied to be a front for inner feelings of inadequacy and shame, possibly related to his repressed sexuality. Mac's obsession with fitness and the dramatic changes to his physique throughout the series suggest an ongoing struggle with his body image.

At the start of season 7, Mac has gained at least 60 pounds (27 kilograms) of fat, which he saw as a step to developing muscle ("cultivating mass" in his words) to go from "a tiny twink to [a] muscle-bound freak." In the episode "How Mac Got Fat," he goes into greater detail about his intentions, explaining that earlier, the Gang had decided to replace themselves with avatars to run Paddy's Pub so they could slack off. Mac's avatar was a bodybuilder. When Dee points out that the avatar does not look like him because he has more muscle, Mac starts gaining weight in an attempt to become the same size as the bodybuilder. Eventually the Gang drops the avatar plan and everything goes back to normal, but Mac is stuck with his dangerous weight gain. The rest of The Gang agrees he looks unhealthy—Dennis is personally outraged by the sight of his gut—but Mac is indifferent to their opinions despite developing diabetes as a result of his new eating habits.

The weight gain was real. Rob McElhenney has stated in interviews that he wanted to make Mac fat as his own way of fighting the trend of actors on TV shows getting more attractive as a show gains success (he specifically talked about The Big Bang Theory and how the nerdy lead characters were better-dressed and had trendier hairstyles as the show became a huge hit for CBS), and that it also made sense that Mac would be aging badly thanks to the reckless, selfish, and stupid lifestyle of which he and the rest of the characters are so proud.[2]

To gain the weight for Season 7 in the healthiest way possible, McElhenney worked with a nutritionist recommended by professional baseball player Chase Utley (who had played himself in the Season 6 episode "The Gang Gets Stranded in the Woods").[3] He ate an average of 5,000 calories a day during the weight gain and lost the weight by returning to his normal eating and workout routines. In the Season 8 episode "The Gang Gets Analyzed" it is revealed in the show that Mac lost his weight from taking 'Size Pills' (Mexican Ephedra) given to him by Dennis who found him to be 'disgusting' when he was overweight. We also find out that Mac preferred being overweight as it made him 'scary' to other people.