Shawn Michael's is undertakers next opponent at WrestleMania 26.
The Undertaker defeated Triple H at WrestleMania 27.
No one knows yet. That hasn't been revealed.
The Undertakers first Wrestlemania was Wrestlemania 7, which was where he succesfully beat Jimmy Snuka
John Cena
Batista
NO
It will end the shield Might end it at wrestlemania 30 The streak is never going to end, and the Shield is not facing Undertaker at WrestleMania. It's not happening.
edge
Randy Orton
The Undertakers 21st opponent has yet to be named. It has been rumoured that his opponent will be revealed at SummerSlam 2012 or around that time, before or after. The main rumour for the Undertakers 21st opponent is Brock Lesnar.
He currently has an 18-0 streak on WrestleMania.