The Royal Rumble match is not without its controversy and there have been plenty of examples of wrestlers trying to cheat or use underhanded tactics to win the event, such as hiding outside of the ring, eliminating wrestlers after you have been eliminated, and more.
In terms of underhanded tactics and cheating, Vince McMahon seemed to intentionally spend the majority of the 1999 Royal Rumble actively avoiding conflict and allowing him to eventually win. Jerry Lawler hid under the ring during one of his ring appearances. Both of these bring the question of why don't wrestlers, especially heels, do this more often.
There are also multiple wrestlers who returned to the ring after they were eliminated to take revenge and eliminate a still competing wrestler. Hulk Hogan eliminated Sid Vicious in the 1992 Royal Rumble to help Ric Flair win, Jerry Lawler helped eliminate Mr. Perfect in 1993 and many, many more.
However, this was taken a step further when Steve Austin re-entered the Royal Rumble in 1997 after he was eliminated by Bret Hart, and would later be declared the winner after eliminating Bret Hart.
Some wrestlers never actually made it to the ring. Curtis Axel was laid out by Erick Rowan at the 2015 Royal Rumble. However, Rowan never participated in the Royal Rumble. As opposed to Sami Zayn, who with Kevin Owens, attacked the number 10 participant Tye Dillinger at the 2018 Royal Rumble to take his place. Mick Foley also used this tactic in 2004 when he took out Test and used his entry to eliminate his rival Randy Orton.
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But then there are those select few superstars who go into the ring and decimate their opponents. They clean house and look to eliminate anything that moves. These are superstars who have entered the Royal Rumble in the 24th slot and have gone on to create a massive impact affecting the results of the battle royal encounter.
#5 Kane (2015) - Eliminated 27th - 4 Eliminations
Not many superstars boast of a Royal Rumble record like Kane does. Whenever the Devil's favorite demon enters the ring, there is hell to pay for.
In one of Kane's last few Royal Rumble appearances, the Big Red Machine entered the Royal Rumble as number 24 under his Corporate Kane gimmick. Wrestling in a plain pair of suit pants and sans mask, he entered the Royal Rumble for the second to last time in his career.
Kane added to his elimination tally with the help of fellow Authority member and tag team partner the Big Show, as the two eliminated Ryback, Dolph Ziggler, Bray Wyatt and Dean Ambrose before turning their attentions to Roman Reigns.
When the two big men attacked Reigns, he was granted a save in the form of fellow Anoa'i family member the Rock. As the Rock helped fight off both the Big Show and Kane, Roman Reigns then eliminated the two, leaving himself and Rusev, who was outside of the ring.
The four eliminations from the would put Kane's total elimination tally at 44, overtaking the previous record of Shawn Michaels who sits on 40 eliminations. Kane has since added other eliminations to his tally, leaving the current record standing at 46.
The fact here is that despite being a heel superstar at the time, both Kane and Big Show were cheered on by the fans owing to their hate for Roman Reigns.