Selected by the Philadelphia Flyers in the second round (No. 33) of the 1989 NHL Draft, Johnson had 369 points (145 goals, 224 assists) in 785 regular-season games with the Predators, Blackhawks, Pittsburgh Penguins and Detroit Red Wings, and 13 points (seven goals, six assists) in 37 Stanley Cup Playoff games.
He won a silver medal with Canada at the 1994 Lillehammer Olympics.
"He did everything well," Mason said. "You put him on the power play, he'd find a way to be successful. Put him on the penalty kill, he'd be your best penalty-killer. He was not the biggest player, but he'd go into the corners and outwork you."
Johnson played four years at the University of North Dakota from 1989-93 and was a three-time finalist for the Hobey Baker Award, given to the top men's player in NCAA ice hockey. He is North Dakota's leading scorer with 272 points (74 goals, 198 assists) in 155 games and was inducted into its Hall of Fame in 2013.
"The UND hockey family is saddened to learn of Greg Johnson's passing," North Dakota coach Brad Berry said. "Our heart-felt sympathies and thoughts are with Greg's family and loved ones at this difficult time. He was a Hall of Fame athlete and more importantly, a Hall of Fame man. He will be greatly missed."