- Acting for Two:
- Well, three, actually. Rory Kinnear plays the Orderly, Lucifer and Dracula in "A Blade of Grass".
- Patti LuPone plays the Cut-Wife/Joan Clayton in season 2 and her descendant Dr.Seward in season 3.
- Actor-Inspired Element:
- According to John Logan, Dorian's entire admittedly-anachronistic look came from Reeve Carney, who dresses very similar in real life.
- The entire brainwashing subplot in season two came about because John Logan finds Timothy Dalton so charming and friendly in real life, and wanted to write it into Malcolm's character.
- Actor-Inspired Heroism: Sir Malcolm Murray was initially created with the intention of being the darkest of the cast (who are all anti-heroes), thus whilst still complicated and even at times sympathetic, season one clearly presents him as a selfish, hypocritical, ruthless and at times flat-out abusive man with a long dark past of bloodshed. It was intended he would mostly carry on this role throughout the entire series run; however, series creator John Logan found Creator.Timothy Dalton to be such a friendly and charming person to work with, he decided to incorporate some of this into the character. This led to Sir Malcolm spending a large portion of season two under a spell that made him kinder and more optimistic, and Season three to involve him genuinely developing into a much softer and more heroic individual.
- Conlang: The language used in season two (Verbis Diablo) is a fictional amalgam of Aramaic, Ancient Greek, Latin, and an obscure Arabic dialect called (in phonetic English) "Kan Allah Musali-Algins". Verbis Diablo was created specifically for the show by linguist David J. Peterson, who has also created languages for shows such as Game of Thrones and The Shannara Chronicles.
- Creator's Favorite: Series creator John Logan has admitted that Vanessa and the Creature are his favorites to write for, so much so that in season two, he wrote them a 10-minute scene together, and in season three, crafted an entire episode around the premise of "what if the Creature had been Vanessa's orderly at the asylum?"
- Fake Brit:
- French actress Eva Green plays Vanessa Ives.
- American actor Reeve Carney plays the character of Dorian Gray.
- American actress Patti LuPone plays the Cut-Wife of Ballantree Moor.
- Inverted with British actor Stephen Lord who plays the American Warren Roper.
- American actor Christian Camargo plays the very posh Dr. Alexander Sweet, a.k.a. Dracula.
- I Knew It!:
- After a whole season of telling images in the opening credits, plus wondering about certain characters' ultimate roles in the show, let's just say not too many viewers were surprised that Ethan turns out to be a werewolf and Brona becomes the Creature's intended bride.
- Very few were surprised by the revelation that Dr. Sweet is Dracula. It was almost as if the writers weren't even trying to hide it.
- International Coproduction: Produced in the US by Showtime and for the UK by Sky Atlantic.
- Method Acting: What Eva Green did for the many possession/asylum scenes, according to the director. She would ask to be put in restraints, got water dumped on her, and all of the bruises Vanessa displays in "Possession" are due to her throwing herself around.
- Production Posse: John Logan cast Rory Kinnear (Caliban) and Helen McCrory (Evelyn) due to having worked with them on Skyfall.
- Real-Life Relative: In season three, John Clare's wife Marjorie is played by Rory Kinnear's wife Pandora Colin.
- Recast as a Regular: Patti LuPone and the cast/crew apparently had so much fun working together in "The Nightcomers" that she returned as Doctor Seward for season three.
Trivia / Penny Dreadful