The Hardy Boys cast included: Parker Stevenson as Frank Hardy; Shaun Cassidy (brother of David Cassidy of The Partridge Family) as Joe Hardy; Edmund Gilbert as their father, Fenton Hardy, a private eye; Edith Atwater (to September 1978) as Aunt Gertrude; Lisa Eilbacher (to September 1978) as the boys' friend, Callie Shaw; and Gary Springer (to September 1978) as Chet Morton.
The Nancy Drew cast included Pamela Sue Martin (and Janet Louise Johnson briefly when Martin quit) as Nancy Drew (Martin had balked at the idea of merging the two shows and was replaced when the decision to merge was final); William Schallert as Nancy's widower father, Carson Drew, a criminal lawyer; George O'Hanlon as Ned Nickerson; and Jean Rasey (1977) and Susan Buckner (1977-78) as George Fayne. Glen A. Larson was the executive producer.
The Hardy Boys and Nancy Drew books were both written by the same man, under 2 different pen names.
Hardy Boys / Nancy Drew episode descriptions