#4 Brock Lesnar

Brock Lesnar will defend his WWE Championship at WrestleMania 36 against this year's men's Royal Rumble winner, Drew McIntyre. It will be interesting to see what WWE does with Lesnar if The Beast does lose the title. Lesnar without a top title means that he may not be used on WWE television, and we could see him taking a few months off.
One match that WWE will be foolish not to have this year is between two former Universal Champions - Brock Lesnar and The Fiend. WWE could have had this match last year at Survivor Series when Lesnar was the WWE Champion and The Fiend was the Universal Champion. Instead, Lesnar faced Rey Mysterio and The Fiend faced Daniel Bryan.
For Lesnar to face The Fiend, he will have to move to RAW, which is a possibility, considering the Superstar Shake-Up should happen soon. This is a match that could headline WrestleMania, but if WWE wants to bring back crowds and interest, they could possibly hold it at SummerSlam, in August.