#2 Against The Undertaker at WrestleMania 31
Following The Undertaker's huge loss at WrestleMania 30 against Brock Lesnar, who broke his undefeated streak at WrestleMania, fans started to believe that the Dead Man was done with his career and won't wrestle anymore.
During the build-up to WrestleMania 31, Bray Wyatt started teasing and taunting The Phenom for a match at the Show of Shows. The Undertaker didn't physically show up for the build-up or any confrontation for the match, but he accepted Wyatt's challenge with his supernatural antics.
When this match was made official, it looked like WWE was planning a "passing the torch" moment between the guy who has arguably been the biggest face of fear in WWE for the past couple of decades and a guy who will be carrying forward this legacy and be the new face of fear for years to come.
After his streak got broken, the mystique around his appearance at WrestleMania was highly hurt, and fans were even believing Wyatt would retire Taker handing him his second successive loss at WrestleMania.
This didn't happen though, as the Dead Man defeated Bray at WrestleMania 31 in a convincing manner. While just a match against Undertaker is a huge boost, but a loss didn't really help Wyatt's claim of being the new face of fear. There was no reason for Undertaker to win this match, other than improve his WM record.
I still believe WWE here missed a huge opportunity of creating a new superstar that would have carried forward the legacy of dark forces in WWE.