Which NBA head coach hold the record for the most championships won by an athlete in North America?
1974–75 Seattle SuperSonics season:  In their second season with Bill Russell as head coach and with rookies comprising half the roster, the SuperSonics finished the regular season in 4th place in the Western Conference with a 43–39 record and reached the playoffs for the first time in franchise history. Bill Russell:  Russell holds the record for the most championships won by an athlete in a North American sports league (tied with Henri Richard of the National Hockey League).
Bill Russell