WWE WrestleMania 36: Ronda Rousey and More Surprise Appearances to Watch For

WrestleMania 36 on April 5 is set to feature several massive stars in big-time matches, including Roman Reigns, Brock Lesnar, Goldberg, John Cena, Becky Lynch and The Undertaker. But some even bigger names that haven't been announced could be part of the Showcase of the Immortals as well.

WWE has a long history of not only involving celebrities in the WrestleMania festivities but also providing fans with some unannounced surprises to help make the biggest event of the year even more memorable.

Some primary examples of that in recent years include Ronda Rousey and The Rock taking part in a segment at WrestleMania 31, Basketball Hall of Famer Shaquille O'Neal participating in the Andre the Giant Memorial Battle Royal at WrestleMania 32 and then-New England Patriot Rob Gronkowski getting physical at WrestleMania 33.

Here is a rundown of a few big names that could well have roles at WrestleMania despite the fact that they haven't been mentioned by WWE.

Ronda Rousey has not appeared on WWE programming since WrestleMania 35, but there are some breadcrumbs that suggest her hiatus could end at WrestleMania 36.

Rousey took part in the first women's main event at WrestleMania last year when she faced Becky Lynch and Charlotte Flair in a Triple Threat match. Becky caught Rousey with a crucifix pin and won both the Raw and SmackDown Women's Championships in the process.

At this year's WrestleMania, Lynch will defend the Raw Women's Championship against Shayna Baszler, who is one of Rousey's closest friends. Given Rousey's relationship with Baszler and rivalry with Lynch, it would make plenty of sense for Rousey to show up during or after the match to possibly help or celebrate with Baszler or perhaps even stare down The Man.

Fellow WWE Superstar and former UFC champ Cain Velasquez recently tweeted a photo of himself and Rousey at WWE headquarters in Stamford, Connecticut:

That predictably led to speculation that both Rousey's and Velasquez's WWE programming returns could be in the works.

While Velasquez's return may not have much of an instant impact after his match against Lesnar at WWE Crown Jewel last year flopped, Rousey's return would be a massive deal given the fact that she was the primary focus of the women's division during her one-year run with the promotion.

Fans have been clamoring for a one-on-one match between Rousey and Lynch ever since WrestleMania 35, and WrestleMania 36 would be the perfect place to set the stage for a bout at a later date, possibly at SummerSlam in August.

Like Rousey, Gronkowski is no stranger to the WWE ring and having a surprise involvement at the biggest sports entertainment event of the year.

The former Patriots tight end jumped the barricade at WrestleMania 33 to help his friend Mojo Rawley eliminate Jinder Mahal and win the Andre the Giant Memorial Battle Royal.

Fans have speculated about Gronk signing with WWE ever since, and it may finally be becoming a reality. Pro Wrestling Sheet's Ryan Satin recently reported on FS1's WWE Backstage that WWE and Gronkowski were closing in on a contract:

Shortly thereafter, Tony Maglio of The Wrap reported that it was a done deal and that Gronkowski was scheduled to appear on the March 20 episode of SmackDown and then at WrestleMania 36.

While the future Pro Football Hall of Famer's appearance at WrestleMania isn't guaranteed, it makes plenty of sense if a plan is in place for him to have some matches in the future.

Having Gronkowski either compete in the Andre the Giant Memorial Battle Royal or get involved with it again would make sense, and it could allow WWE to lay the groundwork for a feud. One potential opponent who stands out is King Corbin. In addition to the fact that Corbin is a great heel who is universally hated, he spent some time in the NFL as well, which is something WWE can draw from when crafting a storyline.

SummerSlam is set to take place in Boston, which is essentially Gronk's adopted hometown after spending so many years with the Pats. A Gronkowski vs. Corbin match in Beantown would be a massive draw both locally and nationwide.

Although Kane isn't a mainstream star like Rousey or Gronkowski, The Devil's Favorite Demon making an unannounced appearance at WrestleMania would still be the a big deal.

Kane is one of the most accomplished Superstars in WWE history, but his appearances on WWE programming have been few and far between over the past couple years because of his duties as the mayor of Knox County in Tennessee.

The veteran still shows up on Raw or SmackDown occasionally, though, and if he is free for WrestleMania, there is a perfect spot for him to contribute.

The Undertaker and AJ Styles are scheduled to sign the contract for their WrestleMania match on Monday's episode of Raw, so Taker vs. Styles on the Grandest Stage of Them All is almost certainly going to happen.

If it does, The Deadman will be at a disadvantage, with OC members Luke Gallows and Karl Anderson backing up Styles. In that scenario, perhaps someone could arrive to help even the odds a bit.

Kane would be the ideal candidate since he is The Undertaker's storyline brother and is more synonymous with The Phenom than anyone in WWE history.

Having Kane show up to fight off The OC and take part in a Brothers of Destruction reunion would be a fun piece of business for longtime fans and create another memorable WrestleMania moment for two of the all-time greats.