The Adventure of the Mona Lisa (1912)
The Society of Infallible Detectives was a team of the most well known detectives of the late 19th and early 20th century. However, their adventures seemed to have been a parody, in which the detectives proved ineffectual as a team, mainly because each detective insisted on solving the mystery himself.
The society was led by Sherlock Holmes and came to order at the society's headquarters on Fakir Street in London. They investigated the robbery of the Mona Lisa painting, as well as other crimes.
Membership included: Sherlock Holmes, Dr. Watson, Arsène Lupin, Craig Kennedy, Monsieur Lecoq, Rouletabille, A.J. Raffles (E.W. Hornung), C. Auguste Dupin (Edgar Allan Poe), S.S. "The Thinking Machine" Van Dusen (Jacques Futrelle), Philip Trent (E.C. Bentley), Ebenezer Gryce (Anna Katherine Green), Calvin "Scientific" Sprague (Francis Lynde), Luther Trant (William MacHarg and Edwin Balmer), and M. Eugène François Vidocq.
Source: Public Domain Super Heroes
Sherlock Holmes and a band of his most infallible deductive friends solve mysteries. Infallibly, of course. "The Adventure of the Mona Lisa" appeared in January 1912 in The Century magazine, and "The Adventure of the Clothes-Line" in the same magazine in May 1915.
Mystery and humor writer Carolyn Wells' two crossover stories invented the concept of a modern league of heroes. (Homer and the Argonaut legends did it back in the day.) She also wrote The Technique of the Detective Story, an instruction manual.
Source: The Internet Archive
The International Society of Infallible Detectives is the first superhero team of history. Presided by Sherlock Holmes (Arthur Conan Doyle) and Composed of Arsene Lupin (Maurice Leblanc), Arthur J. Raffles (Ernest William Hornung), the Thinking Machine (Jacques Futrelle), Auguste Dupin (Edgar Allan Poe), Vidocq-Lecocq (Emile Gaboriau), Rouletabille (Gaston Leroux), Craig Kennedy (Arthur Reeve), Luther Trant (William MacHarg and Edwin Balmer), Ebenezer Gryce (Anna Katharine Green) and Dr. Watson (Arthur Conan Doyle).
In their headquarters on Fakir Street, they are waiting for a case worthy of them. When it happens they mutualise their intelligence to solve the mystery. But their solutions are... strange.