Lights Out (1934-1939) is often called the ultimate OTR horror series written and directed first by Wyllis Cooper (1934-1936) and then Arch Obler (1936-1938). Plots varied, but generally were of the crime, fantasy, horror, or supernatural genres. Actors also varied with notable appearances by Boris Karloff. Each episode featured gruesome stories and sound effects. Lights Out is significant for its efforts to provide an immersive experience for listeners, expecting them to shut off distracting stimuli (like the lights) and concentrate on the story. The experiments in stream of consciousness writing and first person narration by Wyliss Cooper provided groundwork for radio drama that followed. Episodes by Arch Obler are among the best remembered of the genre.
Total Episodes (Cooper era): 128
Surviving Episodes: 0
Some surviving scripts were adapted by Arch Obler, who succeeded Cooper.
Total Episodes (Obler era): 211
Surviving Episodes: 57
The Man in the Middle
Episode 07, 25 August 1945
Revised by Arch Obler from a Wyliss Cooper script entitled "After Five O'Clock." Cooper version broadcast 6 March 1935. Obler version broadcast 25 August 1945. Follows the stream of consciousness thoughts of John Phillips, a businessman having an affair with his secretary. With his secretary becoming more infatuated, her brother threatening a good thrashing, and his wife coming to the office the same day, John's guilt and suppressed feelings lead him to a desperate solution.
Episode 40 (10 March 1937), Episode 80, 23 February 1938, and Episode 08, 24 November 1942
Oboler often insisted on specific, gruesome atmospheric sounds for his episodes of Lights Out!. In this episode, the sound of a beating chicken heart, the product of a flawed scientific experiment, threatening the world with its uncontrolled growth, provides the background. The original broadcast is lost. This abbreviated version was recreated by Arch Oboler for his 1962 record album Drop Dead. Script available here. In 1999, The Gotham Radio Players recreated the entire script.
The State Executioner
Episode 41, 17 March 1937
First broadcast 17 March 1937 and again 17 August 1943 (Episode 46). King George III's state executioner revels in putting criminals to their death at the gallows. When he withholds evidence about the innocence of his next victim he quickly wishes he had not.
LIGHTS OUT, EVERYBODY!
This is the witching hour . . . It is the hour when dogs howl, and evil is let loose on the sleeping world . . . Want to hear about it? . . . Then turn out your lights!
Lights Out was created in Fall 1933 by Wyllis Oswald Cooper (1899-1955), who wanted to offer a late night radio program focusing on crime and supernatural thrillers. The first episodes, each 15-minutes in length, were broadcast locally Wednesdays, at midnight, by WENR in Chicago, Illinois, a National Broadcast Company (NBC) affiliate, beginning 3 January 1934. In April, episodes were extended to thirty minutes. Each episode was gruesome, gory, with acting and sound effects to match. In January 1935 the show was cancelled, but returned within three weeks in response to public outcry. In April 1935, NBC began broadcasting Lights Out nationally. Episodes were tamer fantasy and ghost stories, with less emphasis on gore. Cooper left the series in June 1936 for a job in Hollywood writing movie scripts, leaving a legacy of one hundred twenty eight episodes. Apparently none survive. Titles are unknown.
Cooper also wrote scripts for the NBC series Immortal Dramas, the third and fourth seasons of The Campbell Playhouse (29 November 1940-13 June 1941—formally the The Mercury Theatre on the Air which broadcast its last episode on 4 December 1938)—and Quiet, Please! (1947-1948), and Whitehall 1212 (1951-1952). His experiments with stream of consciousness and first person narration were incorporated widely in radio drama years later. 
Cooper passed the writing and directing duties for Lights Out to Arch Oboler in June 1936. Although Oboler credited Cooper as the first person to understand that radio drama is an art form, he established himself as a master as well, turning Lights Out into a nationally renowned series and fixing its focus on the macabre. After hosting many episodes, Oboler left in 1939 to pursue Arch Oboler's Plays, Everyman's Theater, and Plays for Americans. Lights Out! was cancelled following the 16 August 1939 episode, "The Day of the Four." One hundred forty four episodes were produced in this run, all broadcast by National Broadcast Company (NBC). Six survive.
Oboler resurrected Lights Out on 6 October 1942, revising previous scripts and acting as the show's host. Fifty two 30-minute episodes were broadcast from New York every Tuesday night on the National Broadcasting System (NBC), until 28 September 1943. Forty three survive.
During the summers of 1945 (14 July-1 September) and 1946 (6 July-24 August), Lights Out returned on NBC as Fantasies from Lights Out, with episodes based on revised Cooper scripts. Fifteen episodes were produced. Eight survive.
A final effort to revive Lights Out began 16 July 1947, on the Mutual Broadcasting System (MBS). Wyllis Cooper returned, as writer, along with Paul Pierce. Boris Karloff starred. Sadly, the show lasted only a month. Five episodes were produced. Two survive.
Lights Out moved to television in 1949, and ran until 1952, without achieving the popularity of the original radio show.
The show returned a final time, 1970-1973, as The Devil and Mr. O, rebroadcasting Oboler's scripts from 1942-1943. 
Because more episodes and scripts survive from the Obler era, they tend to represent Lights Out.
 A Wyllis Cooper Chronology
 Dunning, John. On the Air: The Ultimate Encyclopedia of Old-Time Radio 1925-1976. Englewood Cliffs, NJ: Prentice-Hall, 1976, pp. 362-363.
Episodes at Internet Archive website
More episodes at Internet Archive website
Episodes at Old Time Radio Researchers Group Library website
Lights Out Radio Logs at Jerry Haendiges Vintage Radio Logs website
The Definitive Lights Out at Digital Deli Too website
Plot summaries and credits at Radio Gold Index website
Scripts at Generic Radio Workshop website