One of the best parts of the Royal Rumble each year is the surprise entrants, and that should be the case again in 2016. A few wrestlers that haven’t appeared in WWE in quite some time, or at all, could take part in Sunday’s 30-man battle royal.

While the Royal Rumble winner usually earns a title shot at WrestleMania, this year’s winner will become the WWE World Heavyweight Champion. Roman Reigns won the title last month and is among the favorites to win the match, but he could lose the belt to a wrestler that’s set to make his return at the pay-per-view.

WWE has dropped a few hints regarding who might appear in the Royal Rumble. On "Monday Night Raw,” announcer Byron Saxton said Reigns “could find himself facing six Royal Rumble winners.” Brock Lesnar, Alberto Del Rio and Sheamus have been confirmed for the match, but who are the other three?

Triple H won the Royal Rumble in 2002, and he’s almost certain to enter the match. The COO hasn’t appeared on “Raw” since he was attacked by Reigns at TLC, but he’s the favorite to win the WWE World Heavyweight Championship on Sunday, setting up a potential title match with Reigns in the main event of WrestleMania 32.

With two spots left for former Royal Rumble winners, there’s certainly a chance that The Undertaker could be one of the 30 entrants. The Deadman hasn’t competed in the match since 2009, but he wrestled more in 2015 than he had in the last few years. Instead of just showing up for WrestleMania, The Undertaker was a part of the Battleground, SummerSlam, Hell in a Cell and Survivor Series PPV’s. Without a clear opponent for WrestleMania 32, the Royal Rumble could help set up The Undertaker’s next big match.

Other former winners that can’t be ruled out as surprise entrants include Randy Orton, The Rock, and even Vince McMahon. Orton has been injured since October, but he recently denied reports that he needed neck surgery. It’s unknown if The Rock will wrestle at WrestleMania 32, but he will be at the PPV and an appearance on Sunday could help set up a match in Dallas. Vince has done all that he can to get the title off Reigns, so it wouldn’t be shocking for him to insert himself in the match and try to screw the current champion.

AJ Styles has never even appeared on a WWE PPV or “Raw,” let alone held the company’s top championship, but he’s among the leading candidates to be a surprise entrant in the 2016 Royal Rumble. Styles has reportedly signed with WWE, possibly set to make his debut at the PPV or the night after on “Raw.” John Cena has sparked more rumors that Styles could appear in the Rumble, posting a picture on Instagram of the wrestler that’s made his name with TNA and New Japan Pro-Wrestling.

Cena underwent shoulder surgery two weeks ago and will miss the Royal Rumble. It’s almost certain that concussion issues will keep Daniel Bryan out of the match, as well. Even if Bryan was medically cleared before Sunday’s PPV, it’s unlikely that he’d be in the match. Bryan would have little chance of winning this year’s Royal Rumble, and fans booed for much of the PPV in each of the last two years when it became clear that he wouldn’t win the battle royal.

It's unknown if an NXT wrestler will be in the match, though it’s not impossible that NXT champion Finn Balor could be one of the 30 participants. Bo Dallas spent nearly 22 minutes in the 2013 Royal Rumble when he was still in NXT.

Bubba Ray Dudley and Diamond Dallas Paige were among the biggest surprises last year. Perhaps the most memorable surprise in recent years was Chris Jericho's return in 2013 when he was the No.2 entrant.