James Moriarty

Professor James Moriarty is Sherlock Holmes's most famous enemy. A former mathematician, he chose to use his exceptional intellectual skills in the criminal area. Why exactly? We don't know for sure. What we know is that Sherlock sees in him his dark ego, gifted with the same powerful mind, and thus the most dangerous criminal.

Moriarty's character is first introduced in "the final problem", which concludes the first serie of Homes adventures. Tired by the celebrity of his hero, Doyle wanted to "kill" him. But Sherlock Holmes couldn't been killed by anyone. He needed an opponent as extraordinary as himself.

About Moriarty, we know mainly what Holmes says to Watson: 

"His appearance was quite familiar to me [what does that mean exactly? Did Holmes observe him before this first encounter ?]. He is extremely tall and thin, his forehead domes out in a white curve, and his two eyes are deeply sunken in his head. He is clean-shaven, pale, and ascetic-looking, retaining something of the professor in his features. His shoulders are round from much study, and his face protrudes forward, and is forever slowly oscillating from side to side in a curious reptilian fashion. He peered at me with great curiosity in his puckered eyes."

Here is the drawing made by Sydny Pagent, who illustrated the original publication

Here are the factual data about Moriarty (Doyle's quotations) :
- He has got a brother also named James, a colonel;
- good birth and excellent education
- endowed with a phenomenal mathematical faculty; wrote a treatise about the Binomial Theorem at the age of 21, which gave him a Chair in a small university.
- Because of rumours, he was compelled to resign and came to London, where he set up as an army coach.