Bret Hart writing The Undertaker a letter when he left WWF in 1997:
"I wrote 'Taker a letter when I left. I said, 'You have to be the voice of the dressing room and the leader now that I'm gone.' I always felt that I was the leader of the dressing room and looked after everything. If guys had a problem, they could come to me and I'd go to Vince and say, 'This guy has a problem, maybe you can help him.' Then 'Taker stepped in and became that guy. A lot of times he had to straighten out guys like Shawn Michaels and stand up for the other wrestlers. Undertaker was always a force in the dressing room."
Undertaker's match with Roman Reigns at WrestleMania 33:
"I liked his final moment. I enjoyed his last match, and I thought he gave his all. He'll forever be one of the wrestling giants, and he is one of the guys I respected the most."
Bret also discussed Taker being "a man's man," wrestling Taker at SummerSlam '97, Undertaker telling Vince McMahon to go to Bret's locker room after the Montreal screwjob and more.
Source: Sports Illustrated