NBA Champion Paul Silas

Three-time NBA champion Paul Silas, who was LeBron James' first professional coach, has died. He was 79 years old.

Longtime Boston insider Bob Ryan shared the news on Sunday ... writing, "I am very sad to report that the Great Paul Silas has died at age 79. To watch him play was a joy. To be his friend was an honor."

Silas, whose coaching career began in 1980 with the San Diego Clippers, was a decorated player in his own right prior to coaching LeBron's Cleveland Cavaliers in 2003-04.

Long before Silas was a head coach, he was a decorated NBA player -- he was a 2-time All-Star and selected to 5 All-defensive teams.

Paul also won three championships with the Boston Celtics in 1974, 1976, and…