The beauty of the Sherlock Holmes stories is that in each one, we get
to meet new characters. There are few reoccuring characters (apart
from the obvious two), the fixtures of the world. Mrs. Hudson the housekeeper,
Holmes' brother Mycroft, Holmes' nemesis Moriarty, and Lestrade of Scotland
Yard.
The characters outlined here are people with reoccuring roles that we learn about. We hear about Anstruther, Dr. Watson's neighbouring doctor (who seems to spend an inordinate amount of time watching Watson's practice) but never meet him. We only meet Watson's wife briefly after he meets her for the first time in The Sign of Four.
As Sir Arthur Conan Doyle was kind enough to write 60 stories about the Great Detective, these descriptions will be, for the most part, taken directly from the text. There is no better guide to who these people are than the stories they occupy.