Mac performed his first standup routine at the age of eight, impersonating his grandparents at the dinner table for the church congregation.
After losing his mother to cancer (his brother, father and grandmother died not long after), Mac realized the healing power of laughter. He began telling jokes for spare change in the Chicago subway. While working various odd jobs, he eventually established his own weekly variety show at Chicago's Regal Theatre and joined the comedy club circuit in 1977.
Mac's edgy comedy seemed an unlikely fit for television, but after frequent appearances on the series Moesha and gaining wide acclaim for his starring role in Spike Lee's The Original Kings of Comedy in 2000, Mac was primed to create a sitcom on his own terms.
Mac's film career also took off. In 2001, he joined an all-star cast in Steven Soderbergh's Ocean's Eleven, playing a smooth con-artist who assisted co-stars George Clooney and Brad Pitt in high-profile heists.
In 2001, he also co-starred with Chris Rock in Head of State, then replaced Bill Murray's Bosley in Charlie's Angels: Full Throttle(2003) and shared billing with John Ritter in director Billy Bob Thornton's Bad Santa (2003).
In 2004, he took on his first starring role as an aging baseball hero inMr. 3000 and then starred again in the race relations comedy Guess Who? (2005). Mac also reunited with the cast for the sequels Ocean's Twelve (2004) and Ocean's Thirteen (2007).
In 1977 at age 19, Mac married his high school sweetheart, Rhonda, whom he credits with much of his success, particularly as the young couple struggled through the early years of Mac's fledgling career. They had a daughter, Je'Niece, and a granddaughter.
On August 9, 2008, Mac died of pneumonia. More than 6,000 people attended a memorial service for Mac at the House of Hope Church on Chicago's South Side.