The ‘penny dreadful’ was a low form of literature.
At least in the old days; today’s form of the penny dreadful would basically be the 99 cent sex-filled supernatural romance novella-length ebooks for Kindle. In the old days, the penny dreadful were probably considered to be just as raunchy and tasteless as those short ebooks are today. The irony there, of course, is that those penny dreadful have sparked the ideas for hundreds of movies, shows, and now its namesake television show, Penny Dreadful on the Showtime network.
The source article gives a great explanation and some historical fact about the penny dreadful of old: the question I pose to our readers is this: in 100 years, will those cheap, poorly written books on Kindle be as fascinating to us, –as the penny dreadful of the 19th century? I mean, Charles Dickens was first published in a penny dreadful… so what genius could we be overlooking in the Kindle mini-novels?
source: www.worldwidewords.org