Lesnar debuted on WWF television on the March 18, 2002, episode of Raw as a heel, attacking Al Snow, Maven and Spike Dudley during their match, while also being accompanied by Paul Heyman, who was seen giving instructions to Lesnar.
When the brand extension was introduced in the WWF, Lesnar was drafted to the Raw brand.
Later, Heyman was confirmed to be Lesnar's agent and gave Lesnar the nickname "The Next Big Thing".
Lesnar's first feud was with The Hardy Boyz and Lesnar defeated Jeff Hardy by knockout after Hardy was unable to respond to referee Theodore Long at Backlash on April 21, his first official televised match.
The next night on Raw, Lesnar faced off against Jeff's brother, Matt Hardy, and defeated him in the same fashion.
Lesnar and Shawn Stasiak lost to The Hardy Boyz at Insurrextion on May 4 after Stasiak was pinned, but he attacked all the participants after the match.
At Judgment Day on May 19, Lesnar and Heyman defeated The Hardy Boyz.

In June 2002, Lesnar won the 2002 King of the Ring tournament, defeating Bubba Ray Dudley in the first round, Booker T in the quarter-finals, Test in the semi-finals and Rob Van Dam in the finals, earning him a shot at the WWE Undisputed Championship at SummerSlam.
At Vengeance on July 21, Lesnar lost to Van Dam in a WWE Intercontinental Championship match by disqualification.
On July 22, Lesnar joined the SmackDown!
brand.
After a quick feud with Hollywood Hulk Hogan in August 2002, Lesnar defeated The Rock at SummerSlam on August 25 to become the new WWE Undisputed Champion and youngest WWE Champion at age 25.
He also became the second fastest professional wrestler to win the WWE Championship since his debut (126 days) behind only Ric Flair (113 days).
At the time, the WWE Undisputed Championship was being defended on both brands, so Raw General Manager Eric Bischoff expected Lesnar to return on Raw the following night.
However, SmackDown!
General Manager Stephanie McMahon declared that Lesnar was only required to defend the title on SmackDown!
shows and events, prompting Bischoff to establish a new championship for the Raw brand (the World Heavyweight Championship); the WWE Undisputed Championship was then renamed the WWE Championship.

Lesnar's rapid rise to the top of WWE in 2002 led to a feud with The Undertaker, which involved a match at Unforgiven on September 22.
The match ended in a double disqualification, with Lesnar retained the title.
Lesnar faced The Undertaker again at No Mercy, this time in a Hell in a Cell match.
Leading up to the match, in the storyline, Lesnar broke The Undertaker's hand with a propane tank.
Despite Heyman begging McMahon not to let The Undertaker use his cast as a weapon, the request was denied and the match went on as planned.
At No Mercy, Lesnar defeated The Undertaker to retain the title, thus ending their feud.
Lesnar would go on to successfully retain the WWE Championship in a handicap match with Heyman against Edge at Rebellion on October 26.

Lesnar's next opponent was Big Show and Heyman was convinced more than anyone that Lesnar could not win, trying to talk him out of defending the title.
Lesnar refused and defended the championship against Show at Survivor Series on November 17.
At the pay-per-view, Heyman turned on Lesnar, allowing Show to chokeslam him onto a steel chair and pin him to win the title, resulting in Lesnar's first pinfall loss in WWE.
This led to Lesnar turning face for the first time.
Following Survivor Series, Heyman made it clear that Lesnar would not get a rematch, and had snuck a special clause saying so into his contract.
To gain his revenge on Big Show and Heyman, Lesnar interfered in his first title defense, which came against Kurt Angle the next month at Armageddon on December 15, where Lesnar executed the F-5 on Big Show, which enabled Angle to win the WWE Championship.
On the following episode of SmackDown!,
however, Angle introduced Heyman as his manager and, despite promising Lesnar a title shot earlier in the evening, declared that Lesnar still would not get it.
Lesnar's rivalry with Heyman and Big
Lesnar debuted on WWF television on the March 18, 2002, episode of Raw as a heel, attacking Al Snow, Maven and Spike Dudley during their match, while also being accompanied by Paul Heyman, who was seen giving instructions to Lesnar. When the brand extension was introduced in the WWF, Lesnar was drafted to the Raw brand. Later, Heyman was confirmed to be Lesnar's agent and gave Lesnar the nickname "The Next Big Thing". Lesnar's first feud was with The Hardy Boyz and Lesnar defeated Jeff Hardy by knockout after Hardy was unable to respond to referee Theodore Long at Backlash on April 21, his first official televised match. The next night on Raw, Lesnar faced off against Jeff's brother, Matt Hardy, and defeated him in the same fashion. Lesnar and Shawn Stasiak lost to The Hardy Boyz at Insurrextion on May 4 after Stasiak was pinned, but he attacked all the participants after the match. At Judgment Day on May 19, Lesnar and Heyman defeated The Hardy Boyz.
In June 2002, Lesnar won the 2002 King of the Ring tournament, defeating Bubba Ray Dudley in the first round, Booker T in the quarter-finals, Test in the semi-finals and Rob Van Dam in the finals, earning him a shot at the WWE Undisputed Championship at SummerSlam. At Vengeance on July 21, Lesnar lost to Van Dam in a WWE Intercontinental Championship match by disqualification. On July 22, Lesnar joined the SmackDown! brand. After a quick feud with Hollywood Hulk Hogan in August 2002, Lesnar defeated The Rock at SummerSlam on August 25 to become the new WWE Undisputed Champion and youngest WWE Champion at age 25. He also became the second fastest professional wrestler to win the WWE Championship since his debut (126 days) behind only Ric Flair (113 days). At the time, the WWE Undisputed Championship was being defended on both brands, so Raw General Manager Eric Bischoff expected Lesnar to return on Raw the following night. However, SmackDown! General Manager Stephanie McMahon declared that Lesnar was only required to defend the title on SmackDown! shows and events, prompting Bischoff to establish a new championship for the Raw brand (the World Heavyweight Championship); the WWE Undisputed Championship was then renamed the WWE Championship.
Lesnar's rapid rise to the top of WWE in 2002 led to a feud with The Undertaker, which involved a match at Unforgiven on September 22. The match ended in a double disqualification, with Lesnar retained the title. Lesnar faced The Undertaker again at No Mercy, this time in a Hell in a Cell match. Leading up to the match, in the storyline, Lesnar broke The Undertaker's hand with a propane tank. Despite Heyman begging McMahon not to let The Undertaker use his cast as a weapon, the request was denied and the match went on as planned. At No Mercy, Lesnar defeated The Undertaker to retain the title, thus ending their feud. Lesnar would go on to successfully retain the WWE Championship in a handicap match with Heyman against Edge at Rebellion on October 26.
Lesnar's next opponent was Big Show and Heyman was convinced more than anyone that Lesnar could not win, trying to talk him out of defending the title. Lesnar refused and defended the championship against Show at Survivor Series on November 17. At the pay-per-view, Heyman turned on Lesnar, allowing Show to chokeslam him onto a steel chair and pin him to win the title, resulting in Lesnar's first pinfall loss in WWE. This led to Lesnar turning face for the first time. Following Survivor Series, Heyman made it clear that Lesnar would not get a rematch, and had snuck a special clause saying so into his contract. To gain his revenge on Big Show and Heyman, Lesnar interfered in his first title defense, which came against Kurt Angle the next month at Armageddon on December 15, where Lesnar executed the F-5 on Big Show, which enabled Angle to win the WWE Championship. On the following episode of SmackDown!, however, Angle introduced Heyman as his manager and, despite promising Lesnar a title shot earlier in the evening, declared that Lesnar still would not get it. Lesnar's rivalry with Heyman and Big
Brock Lesnar