The Twelfth Doctor, Bill and Nardole strolled past books with the titles The Pilot, Smile, Thin Ice, Knock Knock and Oxygen in a library. (TV: A Time For Heroes)
The Confounding Case of the Planetary Prankster • The Pernicious Plots of the Big Game Hunter • The Dangerous Dilemma of the Dream Doorway • Assassin on the Railroads • The Curious Case of the Weirdling Woods
Some categorisation may be based upon conjecture. Real world information should not enter into this. Additionally, a character's role in the DWU can differ from the real world - their placement here is for categorisation.