Answer
Wayne Gretzky was the last NHL player that Thornton played against from the 1990s era. Gretzky, widely considered one of the greatest hockey players of all time, retired from the NHL in 1999, while Thornton continued to play until 2022. Their final matchup occurred in the 1999-2000 season, when Thornton's Boston Bruins faced Gretzky's New York Rangers.