Penny Dreadful is a horror drama television series created for Showtime and Sky by John Logan, who also acts as executive producer alongside Sam Mendes. The show was originally pitched to several US and UK channels, and eventually landed with Showtime, with Sky Atlantic as co-producer. It premiered at the South by Southwest film festival on March 9 and began airing on television on April 28, 2014, on Showtime on Demand. The series premiered on Showtime in the United States on May 11, 2014, and on Sky Atlantic in the United Kingdom on May 20, 2014. After the third-season finale on June 19, 2016, series creator John Logan announced that Penny Dreadful had ended as the main story had reached its conclusion.

The title refers to the penny dreadfuls, a type of 19th-century British fiction publication with lurid and sensational subject matter. The series draws upon many public domain characters from 19th-century Victorian Gothic fiction, including Dorian Gray from Oscar Wilde's The Picture of Dorian Gray; Mina Harker, Abraham Van Helsing, John Seward, Renfield, and Count Dracula from Bram Stoker's Dracula; Victor Frankenstein and his monster from Mary Shelley's Frankenstein; and Henry Jekyll from Robert Louis Stevenson's Strange Case of Dr Jekyll and Mr Hyde, showing their origin stories as an explorer searches for his daughter. Justine from Justine, or The Misfortunes of Virtue by the Marquis de Sade also appears.

A spin-off series, Penny Dreadful: City of Angels, aired from April 26 to June 28, 2020.