Eight of the ten chapters of The Strange Case of Dr. Jekyll and Mr. Hyde are narrated from the third-person-omniscient perspective. Chapters 9 and 10 are narrated from the first-person perspectives of Dr. Lanyon and Dr. Jekyll, respectively. The eight chapters narrated from the third-person-omniscient perspective are also focused through the perspective of Mr. Utterson. Mr. Utterson is thus the internal focalizer.
As a gothic story, The Strange Case of Dr. Jekyll and Mr. Hyde is unusual. Most gothic stories—for example, Frankenstein, Dracula, and Wuthering Heights—are narrated from the first-person perspective. The reason for this is that the first-person perspective allows the author to more easily create mystery in the story. Mystery is, of course, a key characteristic of the gothic genre. A first-person narrator necessarily has a limited understanding or awareness of the story, and thus, the reader's understanding is also limited. A disadvantage of the third-person-omniscient narrator, therefore, is that the reader can, theoretically, like the narrator, know everything that is happening. The opportunities for the author to create mystery are thus reduced. R. L. Stevenson ameliorates this disadvantage by using Mr. Utterson as the internal focalizer.
Another possible disadvantage of the third-person narrator is that it creates a disconnection between the reader and the characters in the story. We, the readers, are separated from those characters, whereas we would, with a first person narrator, be more immediately and directly involved in the story. When we read Dr. Jekyll's own first-person account of the story in the final chapter of the novel, we perhaps feel more connected to him than at any other point in the story. R. L. Stevenson arguably changes to a first-person narration in this final chapter to encourage the reader to empathize with Dr. Jekyll and thus reassess the presentation of him which has been created in the previous nine chapters.