which novel did this character first appear in?
"A Study in Scarlet"
Sherlock Holmes
First appearing in print in 1887's "A Study in Scarlet", the character's popularity became widespread with the first series of short stories in "The Strand Magazine", beginning with "A Scandal in Bohemia" in 1891; additional tales appeared from then until 1927, eventually totalling four novels and 56 short stories. All but one are set in the Victorian or Edwardian eras, between about 1880 and 1914. 
when did season 4 of sherlock come out 1 January 2017 who is the lead character of this series? Sherlock Holmes who was this character originally created by? Sir Arthur Conan Doyle
wiki:19670721
Sherlock Holmes [SEP] Introduction
Holmes's popularity and fame are such that many have believed him to be not a fictional character but a real individual; numerous literary and fan societies have been founded on this pretense. Avid readers of the Holmes stories helped create the modern practice of fandom. The character and stories have had a profound and lasting effect on mystery writing and popular culture as a whole, with the original tales as well as thousands written by authors other than Conan Doyle being adapted into stage and radio plays, television, films, video games, and other media for over one hundred years.