The original Silver Age House of Secrets series ran 80 issues, from November/December 1956 to September/October 1966. In addition to short, 'one-off' stories, several issues beginning with No. 23, August, 1959 featured the adventures of modern-dress sorcerer Mark Merlin. The dual-personality Eclipso ("Hero and Villain in One Man!") was introduced in issue #61 (Aug. 1963), continuing to the series' end. Prince Ra-Man the Mind-Master bowed in #73 (Oct. 1965) (later retconned into being the same person as Mark Merlin). Other, lesser continuing features included "Peter Puptent, Explorer"; "Dolly and the Professor"; "Doctor Rocket"; and "Moolah the Mystic". The title was cancelled after #80, dated September–October 1966.
The series was revived three years later with a definite article as The House of Secrets, beginning with issue #81 (Aug.-Sept. 1969). Now its horror and suspense tales were introduced by a host named Abel, who would also host the satirical comic Plop!. His brother Cain hosted House of Mystery. Swamp Thing first appeared in House of Secrets #92 (July 1971) in a stand-alone horror story set in the early 20th century written by Len Wein and drawn by Bernie Wrightson. The woman appearing on the cover of this issue was modeled after future comics writer Louise Simonson.
This revival, sporting many covers by Neal Adams, Bernie Wrightson, and Michael Kaluta, ran through issue #154 (Nov. 1978), with three months passing between #140 (April 1976) and #141 (July 1976). It was then 'merged' into The Unexpected with issue #189, through issue #199. The series was 68 ad-free pages, allowing all three portions to be full-length issues.