MacMillan was a Memorial Cup Champion in 1960 with the St. Michael's Majors, and then he spent six years in the NHL.
He played for the Toronto Maple Leafs, Atlanta Flames, and New York Islanders. Billy had 151 points in 446 games in his career.
After his career, he became Stanley Cup Champion as an assistant coach in 1980 with the New York Islanders.
After that, he became the first ever coach of the New Jersey Devils. He also holds a place in the Prince Edward Island Sports Hall of Fame.
Rest in peace, Billy.
Source: Torontosun