The hockey world is mourning the passing of John Muckler, who served as a NHL coach, assistant coach and executive throughout parts of five decades.

"The Oilers Hockey Club is saddened to report the passing of our former Head Coach, five-time Stanley Cup champion & dear friend of the organization John Muckler," said the Edmonton Oilers on their social media accounts.

Muckler was part of the staff that put together the Oilers dynasty of the 1980s, joining Edmonton in '82 as an assistant coach under Glen Sather before going on to win five Stanley Cups with the organization between '84 and 1990 -- the last one as head coach.

Muckler also served as head coach of the Buffalo Sabres, Minnesota North Stars, and New York Rangers, and was the GM of the Ottawa Senators from 2001 to 2007. His final NHL role was with the then Phoenix Coyotes. He worked as a senior advisor while the team was coached by Wayne Gretzky.

"He was tough, strict, but most importantly fair, and he helped lay the groundwork to make our team more accountable to each other which propelled us to become champions," Gretzky said in a statement released by the Oilers.

Muckler was 86 years old at the time of his passing. Our sincere condolences to his family, friends and fans.