Phillip Jack Brooks (born October 26, 1978), better known by his ring name CM Punk, is an American professional wrestler and actor. As of November 2023^[update], he is signed to WWE, where he performs on the Raw brand and is the World Heavyweight Champion in his record-tying second reign. Regarded as one of the greatest professional wrestlers of all time, he is known for his outspoken and confrontational straight edge persona, which is based on his real-life experiences. His 434-day reign as WWE Champion is the 10th-longest world title reign in the company's history.

Brooks began his wrestling career on the independent circuit in 1997. He signed with Ring of Honor (ROH) in 2002, where he won the ROH World Championship once and was one of the inaugural inductees into the ROH Hall of Fame in 2022. Brooks signed with WWE in 2005 and won the WWE Championship twice, the World Heavyweight Championship three times, and the ECW Championship, the Intercontinental Championship and the World Tag Team Championship once each. Brooks also won the Money in the Bank ladder match in 2008 and 2009 (making him its only back-to-back winner), was named Superstar of the Year at the 2011 Slammy Awards, and was voted PWI Wrestler of the Year in 2011 and 2012. After acrimoniously leaving WWE in 2014, Brooks retired from wrestling but returned in 2021 when he joined All Elite Wrestling (AEW), where he won the AEW World Championship twice. Brooks was fired in September 2023 after backstage controversies and returned to WWE two months later, where he has since headlined multiple major pay-per-view and livestreaming events, including WrestleMania 41 – Night 1, and won the newer version of the World Heavyweight Championship twice.

Outside of wrestling, Brooks pursued a career in mixed martial arts and joined the welterweight division of Ultimate Fighting Championship (UFC), losing via submission to Mickey Gall in his professional debut at UFC 203 in 2016. He lost his second fight to Mike Jackson via unanimous decision at UFC 225 in 2018, which was later overturned to a no contest; he never fought again and officially retired in August 2021. He worked as a pundit on WWE Backstage (2019–2020) and has been a part-time color commentator for Cage Fury Fighting Championships since 2018. He also starred in the horror films Rabid (2019), Girl on the Third Floor (2019), and Jakob's Wife (2021), as well as the wrestling drama series Heels (2021–2023).

Phillip Jack Brooks was born in Chicago, Illinois, on October 26, 1978. He is the youngest son of housewife Harriet Jadwiga (née Kowalski; 1946–2016) and electrician Daniel Brooks. His mother was born in Germany to Polish parents, while his father had Irish ancestry. Brooks' umbilical cord was wrapped around his neck upon birth, causing his face to appear blue. He and his estranged older brother, Michal, were raised in Lockport, Illinois.

Brooks' father struggled with alcoholism, which led him to adopt a straight edge lifestyle as a teenager. His mother, whom he was also estranged from, suffered from bipolar disorder; he later reportedly obtained a restraining order against her in June 2013. Due to his turbulent childhood, Brooks was welcomed into the family of his childhood best friend, Chez. His first job was at a comic book shop named All American Comics in Evergreen Park, Illinois, which closed in January 2022. "Rowdy" Roddy Piper was an early influence on Brooks; he cites him as the reason he pursued professional wrestling. He was arrested multiple times during his time as a student at Lockport Township High School.

Brooks' first venture into wrestling was a stint in a backyard wrestling federation called the Lunatic Wrestling Federation with his older brother Michal and their friends in the mid-to-late 1990s. He had his debut match on October 25, 1997, the day before his 19th birthday, defeating Brawn the Lumberjack. He first started using the ring name CM Punk when he was put into a tag team named the "Chick Magnets" with CM Venom after another performer skipped out on the card; the "CM" originally stood for "Chick Magnet" but was later amended to have no meaning. Unlike his friends, Punk genuinely wanted to be a wrestler and saw it as more than simple fun. When the promotion started taking off while doing shows out of a warehouse in Mokena, Illinois, Punk found out that Michal had embezzled thousands of dollars from the small company, causing them to become estranged; they have not spoken since.

After leaving the Lunatic Wrestling Federation, Punk enrolled as a student at the Steel Dominion wrestling school in Chicago, where he was trained by Ace Steel, Danny Dominion and Kevin Quinn to become a professional wrestler. As part of the training, he began wrestling at Steel Domain Wrestling in St. Paul, Minnesota, in 1999. It was in the Steel Domain that he met Scott Colton, who soon adopted the ring name Colt Cabana. Punk and Cabana became best friends and spent most of their early career together working in the same independent promotions, as both opponents and tag team partners. In the independents, along Cabana and other fellow Steel Domain graduates Chucke E. Smooth, Adam Pearce, and manager Dave Prazak, Punk formed an alliance named the Gold Bond Mafia.

In 2002, Punk became the International Wrestling Cartel (IWC) Heavyweight Champion, in Monroeville, Pennsylvania. Punk would compete in the company's Super Indy tournament, but never won the championship.