Who is Frank Randall from Dragonfly in Amber and what is their importance?

Frank Randall is Claire's husband. When she passes through the stones, Frank is left behind, fearing for her life, as she disappeared without a trace. Having served his country for six long years, Frank returns home to his wife and pursues an interest in his family history. Frank figured prominently in earlier novels, but in the Dragonfly in Amber, he passes away early in the novel.