An epoch, not merely an era, appears to be coming to an end.

Glen Sather, The Last Lion of Winter, is believed on the verge of informing Garden chairman James Dolan that he will step down as a president of the Rangers as of the end of the season, informed sources have told The Post.

The expected departure of Sather, who has been the club president since June 2000 and doubled as general manager from 2000 through 2014-15, will create uncertainty in the New York front office that has been a model of stability for the last 19 years.

For it is unknown how Sather’s departure and the hiring of a new president to run the hockey department would impact general manager Jeff Gorton. Sather, of course, selected Gorton to be his successor after first hiring him over the summer of 2007.

Incoming bosses tend to hire their own people, even if not immediately.

Sather, 75, would be retiring with five Stanley Cup notches on his belt, all won in Edmonton within a seven-year period from 1984 through 1990 with the powerhouse he built in the front office and coached for the first four of those championship runs.

At one point while working for the small-market, cash-strapped team that hit the skids in the late ’90s, Sather observed that if he had the same budget as the Rangers, his teams would win the Stanley Cup every year.

Well, not quite, but following four seasons in which his Rangers teams failed to make the playoffs in the pre-cap era (and 90 games behind the bench between the firing of Bryan Trottier and the hiring of Tom Renney), Sather produced an entertaining and successful team that qualified for the playoffs in 11 of 12 seasons, went to the Cup final in 2014 before losing to the Kings in five games, and won the Presidents’ Trophy in 2014-15.

Sather, who had the foresight to build around Jaromir Jagr and No. 68’s own band of Czechmates coming out of the 2004-05 canceled season, has been a lightning rod for Rangers fans, rarely given credit for the team’s success and often pilloried for making ultimately unsuccessful deals that sacrificed the future in an attempt to win the Cup.

Sather broke into the NHL with the Bruins’ pre-Cup teams of the latter ’60s. He bounced around the league, even spent some time with the Rangers, acquired by Emile Francis during the 1970-71 season in exchange for Syl Apps Jr. Oops. But he found his home and made his mark in Edmonton, where he was a father figure to the young Wayne Gretzky, Mark Messier, Paul Coffey, Glenn Anderson and Grant Fuhr, and where he won his final Cup two seasons after being ordered by owner Peter Pocklington to trade No. 99 to Los Angeles.

One of the game’s great characters, Sather’s presence has largely been muted as he has worked behind the scenes the last few seasons with Gorton. Now it appears that this legendary figure is about to go off into the good night with his wife, Ann.

With that, an epoch ends in the NHL, an era ends in New York, and at the moment, it is impossible to gauge the ramifications on Broadway.