From: ep 2.2
Character Names: Most major characters in this episode are named directly from the novel on which this episode is based: The Hound of the Baskervilles. Below are the character names and parallels in the story:
Henry Knight: The young heir to Baskerville Hall is named Sir Henry, and he is the inheritor of the house as well as the curse of the Hound from his father. The fact that young Henry’s surname is Knight is obviously a nod to his title in the book.
Corporal Lyons: Laura Lyons is a pivotal character in the book, having vital information about the murderer.
Major Barrymore: Barrymore is the butler at Baskerville Hall, and sports a square-cut black beard. Major Barrymore is similarly in charge of Baskerville the lab, and similarly sour in temperament as well. A delightful tidbit from the Blu-Ray commentary is that of course being in the Army, Barrymore would not have been allowed to have his beard, but the creators made him have one anyway, to more closely resemble his book counterpart.
Dr. Frankland: The bombastic father of Laura Lyons is fond of lawsuits and owner of a big telescope, which is very
helpful at one point of the story.
Dr. Stapleton: Mr. Stapleton is a naturalist (sort of close to the scientist the female version is in the ep), and lives on the moor with a woman he calls his wife, but neither ends up being what they seem. Come to think of it, I can’t find Beryl Stapleton/Garcia’s parallel in this episode. Anyone notice something I’ve missed?
Dr. Mortimer: The family doctor is the one in the book who comes to Holmes in the first place, asking for his help. He saw the crime scene of Henry’s father, Charles’ death, and his beseeching phrase is quoted directly in the episode: “Mr. Holmes, they were the footprints of a gigantic hound!”
Selden: The prisoner hiding out on the moor doesn’t actually show up in the episode (other than a perplexing mention by one of the landlords of the Cross Keys Inn when we first meet them), but when Watson is exploring what he thinks is Morse code and comes across the makeout site, one can overhear a woman in an occupied parked car exclaim, “Mr. Selden, you’ve done it again!”
Fletcher: Not a character from the book itself, but a friend of Doyle’s irl who suggested the story’s main plot of the ghostly dog and curse. Fun fact: the scene where Sherlock baits Fletcher with a fake bet is from “The Blue Carbuncle,” when Holmes does almost identically the same thing to the goose-seller to get information.