Clement was 92 and was the oldest living Welsh international until his death. He made six appearances on the wing for Wales in 1937 and 1938 and also toured with the Lions in South Africa in 1938, playing in six matches.
But it was as the union's secretary that he made his biggest mark on the game in Wales. After taking over from Eric Evans in 1956 he served for 25 years before retiring at the end of the WRU Centenary season in 1981.
He was awarded the OBE for his services to rugby in the New Years Honours list in 1981 and will be remembered as the man who, along with treasurer Ken Harris, helped to oversee the rebuilding of the old Cardiff Arms Park.
"Bill Clement was a great servant to Welsh rugby both as a player and an administrator," said WRU group chief executive Roger Lewis.
"He had the most famous and recognised signature in the game because it appeared on the bottom of every Welsh rugby international ticket during his 25 year tenure as secretary.
"During his time in office the WRU led the world game in the coaching revolution, rebuilt the Arms Park and won three Grand Slams. He commanded huge respect both at home and around the rugby playing world.
"Our thoughts are with his family at this difficult time and our thanks go out to him for the service he gave to our game."
Born on 9 April, 1915, Bill Clement attended the Llanelli County School and briefly played for Felinfoel before joining the Scarlets. He won his six Welsh caps from Llanelli and was their captain in the 1938/39 season.
During World War II he served as a Major in the 4th Battalion, The Welsh Regiment and was awarded the Military Cross in 1944 after the Battle of the Bulge.