Roman Reigns is undeniably the top dog in WWE these days. He is the universal champion and has ruled over SmackDown with his golden fist ever since he returned with a new attitude at SummerSlam on August 23.

The babyface who became the most divisive Superstar on the roster was gone. After turning heel, The Tribal Chief has become one of the most lauded stars in the company.

His alliance with Paul Heyman wasn't necessary for him to get over but it has allowed his character to give orders through a representative instead of always having to do it himself, which further illustrates his power.

The way he has manipulated Jey Uso into doing his bidding has made him even more despicable and provided us with some of the best segments in 2020.

There is little doubt he will continue to hold the title until WrestleMania 37, but the question WWE has to deal with is who to pair him with for the marquee pay-per-view. The SmackDown roster has a lot of talented performers but only a handful have the star power to carry a major program with him.

Let's look at the five most likely candidates to challenge Reigns for the Universal Championship at WrestleMania 37. 

Seth Rollins

Seth Rollins has been away from WWE programming for a while after the birth of his and partner Becky Lynch's daughter, Roux. 

The Messiah lost to Murphy on the November 20 episode of SmackDown and then allowed himself to be eliminated at Survivor Series when he told Sheamus to take him out "for the greater good," whatever that means.

WWE has used Superstars' real lives as part of their characters before, so it's possible Rollins will return as a babyface after his child gave him a new outlook on life.

If that happens, it would not be surprising if he was immediately thrust into a feud with Reigns for the universal title. Not only do they have years of history to use for the storyline, but their roles would also be reversed when it comes to the hero and villain of the story.

Whenever they step into the ring together, they put on a great show. When it comes to Superstars who are capable of putting on a good WrestleMania main event, Rollins will always be on that list. 

Of course, this all hinges on Rollins returning in time for a proper buildup. If he decides to take as much time as possible to spend with his family, we might not see him until after The Show of Shows anyway. 

Shinsuke Nakamura

It's hard to say whether Shinsuke Nakamura turned babyface on Friday's SmackDown, but a lot of people on social media seemed to feel that way after he wrestled a clean match against Daniel Bryan and shook his hand when it was over.

If WWE does intend to turn The King of Strong Style back into a face and return him to the singles division, he would be a great choice to face Reigns on The Grandest Stage of Them All.

Regardless of how WWE has booked him, Nakamura is a main event competitor in every sense of the word. He can work with the biggest stars at the most important events and never feel out of place.

Whether he earns a shot by winning his second Royal Rumble or by some other means, Nakamura vs. Reigns would be a fantastic WrestleMania matchup. 

Big E

Big E is on a roll. He has picked up some big wins in recent weeks and defeated Sami Zayn to win the IC title on the Christmas edition of SmackDown.

The powerhouse of The New Day is one of the most physically impressive Superstars on the entire roster, but the real strength of his character comes from his charisma.

If WWE wants a match the fans can get behind for WrestleMania, having the IC champion challenge Reigns in a title vs. title match would fit the bill.

Despite being in the same company for many years, the two men have not been in the ring together many times. Management can build up a brand-new feud without having years of baggage to work around.

This bout would be hard-hitting and fast-paced. Even if Big E didn't win the universal title, just being in a WrestleMania main event would elevate him to new heights and prepare him for when he does eventually win a world championship. 

Brock Lesnar

Whenever WWE needs a big match to sell a major PPV, you can bet Brock Lesnar is on the shortlist of potential opponents. 

Reigns and The Beast Incarnate have been in the ring together many times over the years, but the dynamic would be so much different now.

The big appeal to this feud would be seeing who Paul Heyman sides with. He has advocated for both Superstars but they could force him to choose as part of the storyline.

The Beast has been his main client for years but he has turned on him before, so it's not impossible for it to happen again. If anything, it would be the more satisfying option for him to side with Reigns.

With Jey Uso as the ace up The Tribal Chief's sleeve, Lesnar would be the underdog in this scenario, which is not something that can be said often. 

Daniel Bryan

WWE has teased a potential match between Bryan and Reigns a few times in recent months, but it seems like management is saving it for the right time—and that could be at WrestleMania 37. 

Bryan was among the first stars to declare himself for the Royal Rumble this year. It's one of the few accolades he has yet to win in WWE, and he is one of the favorites to be the last man standing in the men's match. 

Despite his success, The Yes Man will always be an underdog in matches like this. With Reigns being the most dominant star on SmackDown, Bryan would have an even bigger challenge than usual. 

This is the most likely option for a WrestleMania matchup and also one of the most desired. Bryan is a wily veteran and Reigns is at his best. Putting them in the ring together is guaranteed to produce a great performance worthy of the main event of the biggest WWE show of the year.

The five men on this list are all potential candidates but they are not the only options. Who else would make a good WrestleMania opponent for Reigns? Let us know in the comments section.