Chuck Howley - 50 years after last game.

"Named MVP of Super Bowl V, making Howley the first defensive player and first non-quarterback to win the award … Also holds the distinction of being the only player from a losing team to be named MVP of the Super Bowl." Against the Colt's on a questionable call.

The next year he won a SB, with Lilly.
Should have been in decades ago. And they say there is no Cowboy bias. He was the second best outside linebacker in the NFL in that era. Behind only Bobby Bell of Kansas City.