Mr Thomas was chairman and also a mayor of Gorseinon Council, on which he served for 16 years. He was devoted to his town and fully committed to the community.
He was a regular contributor from the floor at WRU annual general meetings where his good humoured speeches would always leave a mark.
Dennis Gethin, president of the WRU, said: "Morlais was one of the true characters of Welsh rugby. He was a champion of the grassroots game and the WRU Annual General Meeting will never be the same without his presence.
"He kept us all on our toes over the years and his heart was in the right place for the betterment of the game. He will certainly be missed.
"Morlais was hoping to be at the unveiling of Sir Tasker Watkins' statue last Sunday. The two were good friends and enjoyed a great repartee at the AGMs over the years. It was ironic therefore that I received the news of his death shortly after the unveiling ceremony."
Mr Thomas's funeral takes place at St Catherine's Church, Gorseinon on Saturday at 9.45am, followed by burial (family-only) at Kingsbridge Cemetery.