The WWE's traditional January Pay-Per-View (PPV), the Royal Rumble, combines the rules of Battle Royals with the unique gauntlet style entrances that make the event so unique. The Royal Rumble tradition began back in 1988, but there was no reward for winning the Royal Rumble until 1992.
In 1992, the WWF World Championship title was vacated, and it was declared that the winner of the match would be crowned the champion. However, in 1993 the rule was made that the winner of the Royal Rumble would face the Champion at Wrestlemania for the belt.
The 1992 rule of having the belt on the line was resurrected for the 2016 Royal Rumble with Roman Reigns being forced to put his WWE Championship on the line at the Royal Rumble and start the Rumble as the first entrant.
The winner of the Rumble hasn't always been successful in their endeavors at getting the belt, with the Champion retaining their belt 10 out of the 24 times that they have faced the winner of the Royal Rumble. The winner of the Royal Rumble doesn't always compete for the belt as well, with Steve Austin's victory from the 1997 Royal Rumble stripped, and Vince McMahon surrendered his 1999 Royal Rumble opportunity instead of facing the Rock at Wrestlemania for the belt.
Randy Orton also forfeited his chance at the belt after winning the 2017 Royal Rumble, but after turning on Bray Wyatt he defeated AJ Styles to gain his spot back before beating Wyatt again for the title at Wrestlemania.
The Wrestlemania spot has also been put on the line in a match between the winner and an opponent of their choosing, including by Shawn Michaels, Triple H, Rey Mysterio, John Cena, and Roman Reigns.
You can see the other entries in this series below:
Part 1 is here
Part 2 is here
Part 3 is here
Part 4 is here
Part 5 is here