Brock Lesnar is famously temperamental and sometimes hard to get along with. As one of the most decorated combat sportsmen of all time, he knows what he's worth and he isn't afraid to let out his frustration when things don't go his way.
There have been multiple instances of Brock Lesnar losing his cool backstage. Some of these small, some more serious.
#5 Backstage fight with Matt Hardy
Brock Lesnar has never been the most easy-going guy, even during his first run in the WWE. Matt Hardy recalled how he was working with Brock Lesnar on the main event of SmackDown. He said that Lesnar was upset throughout the day that the match was going to go 12 minutes with Hardy getting a lot of offense in.
Matt said that Brock kept requesting for changes to be made throughout the day and this angered him. So much so that Hardy hit Brock hard in the head with a steel chair during the match.
Matt revealed that Lesnar was incensed backstage and that Vince McMahon and Fit Finlay had to personally intervene to calm things down.
Speaking in an interview years later, Matt Hardy described how it all went down:
"I caught him with lip of the chair in the back of his head and I split his head open, there was a scar, it was brutal. ...I remember coming to the back and telling Shannon Moore, 'I ****** him up, he is not going to be happy' I gotta go twelve minutes with Brock Lesnar, I know he wants to kill me. I just remember him coming through Gorilla [Position] and he's like, 'What the ****?! What the ****, Matt!' "
Hardy also added that despite all this, Brock had always been a professional inside the ring.