WWE - and pro wrestling in general- is a team sport, of sorts. Wrestlers are aware that the only way to put on a fantastic match is to work with your opponent and try to make each other look their best.
Several WWE stars have had issues with their opponents in the past and didn't want to work with them. There are also moments when WWE's creative team has told the stars that there will be a certain end to a match, so they have had to injure their opponents for real for the sake of the storyline.
While many wrestlers don't go out their way to intentionally hurt anyone else, there are a few who have gained that kind of reputation and have been known to injure stars intentionally in the past.
#5. Alberto Del Rio vs. Sin Cara (WWE RAW, 2013)
Alberto Del Rio is a former World Champion, but his issues with Sin Cara became well known throughout his time contracted to WWE. Del Rio faced off against the masked star on an episode of RAW back in 2013 and it's believed that the first kick of the match broke his finger.
Sin Cara called for the match to prematurely end due to the injury and it was obvious that Del Rio wasn't impressed. In an unscripted moment after the referee had called to finish the match, The Mexican star rolled his opponent into the ring and kicked him hard in the ribs.
The referee was then forced to hold Del Rio back from attacking Cara further as he continued to scream at him in front of the live audience. The Wrestling Observer reported that this led to backstage heat on Sin Cara for finishing his match early when many stars would have continued despite the injury.
Del Rio and Sin Cara had heat for much of their WWE career and this was just one of the times where this boiled over into the ring.
#4 Brock Lesnar vs Braun Strowman vs Kane (WWE Royal Rumble 2018)
Brock Lesnar took on Braun Strowman and Kane in a triple threat match for the Universal Championship at The Royal Rumble back in 2018. This was Strowman's first big moment in a WWE ring and it appears that he got ahead of himself when he was in the ring with Brock Lesnar.
The Beast Incarnate was knee'd in the face as Strowman attempted to rush through his spot and was forced to act to calm him down. Lesnar delivered a punch to the face of Strowman, which was a clear, stiff punch to slow him down and take him off his feet.
This was followed by the former WWE Champion telling The Monster Among Men to calm down so that they could continue the match. If Strowman had continued at that speed, then someone would have been injured. Lesnar wanted to hit Strowman hard enough to make him see that he needed to slow down and it was something that the two men laughed about backstage following the match.
Both Strowman and the former WWE Champion have worked together since without any issues.
#3. Daniel Puder vs Kurt Angle (WWE SmackDown, 2004)
The match between Olympic Gold Medalist Kurt Angle and 2004 Tough Enough contestant Daniel Puder has been told many times over the past 15 years. At the time, Angle was seen as a legitimate tough guy in WWE and on an episode of SmackDown, he challenged the Tough Enough contestants to an amateur wrestling match.
After a match which saw Chris Nawrocki's ribs get broken, Daniel Puder stepped in and managed to lock Angle in the Kimura Lock which was somewhat embarrassing for the Olympic Champion. Puder was about to break Angle's arm before the referee thought fast and counted a pin even though Puder's shoulders weren't actually flat on the mat.
This later led to Puder being welcomed to WWE in the roughest of ways at the Royal Rumble the following year. But it also taught the former Champion a lesson, since he underestimated the talent in Tough Enough that year and it could have been embarrassing for him if the referee hadn't acted fast.
#2 Umaga and Steve-O (WWE RAW, 2006)
Back in 2006, Monday Night RAW took place in Los Angeles and the theme of the episode was 'RAW goes Hollywood'. One of the guests for the show included Jackass star Steve-O. Of course, being the adrenaline junkie that he is, Steve-O wanted to get into a WWE ring but got more than he bargained for when he was put up against Umaga.
The beatdown ended with a top rope splash from Umaga, but while other WWE stars then stay down and sell the move, Steve-O continued to move around. Umaga wasn't too pleased with Steve-O 'no-selling' his move.
The former Champion was then forced to legitimately go over and deliver a number of blows to the star in order to stop him from moving around in the ring. Steve-O then later publicly claimed that he had suffered a concussion after being in the ring with the Samoan Bulldozer.
There were reportedly plans for The Jackass Crew to take on The Samoan in a handicap match at SummerSlam, but after this beat down, all of those plans were nixed.
#1. Brock Lesnar vs Randy Orton (WWE SummerSlam 2016)
The end of the match came when the Beast Incarnate hit Orton with a number of elbows to the head and legitimately busted him open. The 12-time WWE Champion suffered a concussion and was left in a pool of his own blood when it was announced that the match had ended via TKO.
Following the match, Orton told USA Today that he was annoyed that he suffered a concussion and was out of action in WWE for three weeks.
"The fact that I had a concussion and was out for three weeks and wasn't able to do anything p****ed me off. We say this a lot in the back when someone gets hit harder than intended, we knew what we were signing up for. It's a rough sport. It's a rough business and very physical. A few more people need to respect how things can go sour out there."