Hope you all noticed that I wrote 'Watsons' instead of 'Watson'. No, that wasn't a typo; the whole point was to tell you that I'm trying to type both the canon characters and their newer incarnations in the Guy Richie films and the series Sherlock (BBC) and Elementary (CBS). I'll attempt some other characters too, like Mycroft Holmes, Inspector Lestrade, and Irene Adler.
First of all, I've seen so many type the canonical Mycroft as an INTP. That's probably true. He is first and foremost a theoretician; according to his brother, he doesn't bother proving that he is right as long as he knows he is - very INTP in my opinion: "Let those conventional weirdos make their own mistakes, I know I'm right and I don't care what they think". Hair-splittingly logical, but not overly concerned with being recognized for his brilliance.
What surprises me more is that many people seem to think that Sherlock is INTJ - maybe because of his stereotypically INTP brother, who is quite different from him. But Sherlock seems to me way too unsystematic to be a J, not to mention that his most developed functions strike me as being Ti and Ne. I think both are INTP, but in different ways. To explain the obvious differences, I think the Big Five test is a more appropriate tool than MBTI. They probably share the Openness to new experiences/Conscientuousness/Extraversion/Agreeableness scores (High-low-low-low), which in my eyes seem to equal N-P-I-T in MBTI typing, but the last trait, Neuroticism, is what separates them. Mycroft is a settled type of person, consistent in his habits and seemingly content with his life - a low-scorer on Neuroticism. Sherlock, on the other hand, is prone to mood swings, described by Watson as having 'nervous hands' (could be a sign of inner restlessness), and tends to dramatize things - all indicating a Neurotic personality.
To sum up the canonical Holmes brothers: Two INTPs, one settled and one restless.
The canonical Watson is an ISFP. He describes himself as having been a careless spender, even a gambler on occasions, before he moved in with Holmes; I think an ISFJ would be more meticulous about his money and how he spent them. Furthermore, he's always ready to drop everything at a moment's notice to join Holmes in his adventures - that's Perception all over. He is seen to be critical of the American civil war, while he certainly had some sympathies; this opposition to carelessly wasting lives suggests a Feeler tendency (while a lot of Thinkers could agree with him today, it seems very compassionate compared to his Victorian contemporaries). It lies in the very essence of Watson's existence that he would be a Sensor, as his main role in the tales is to be a catalyst for Holmes' mental processes, which would have seemed incomprehensible if not for the fact that he frequently explains them to someone with a more concrete view of the outside world. As for the I/E dichotomy, I type him as an Introvert because he seems to have few close friends, but is very attached to Holmes; the relationships of an Introvert are usually few but deep, instead of many and superficial.
Then there's The Woman, Irene Adler. Though different from Holmes in most ways, there are still some things that suggests that they are actually kindred souls. To start at the beginning, with the I/E variable, I'd say she's an Extravert. She is a singer, a performer; this indicates an open and energetic disposition. As for S/N, I'm leaning towards S. While she obviously is creative and a bit unconventional, she's still a pleasure-seeking type of person, and I get clear Artisan vibes from her. She's sly enough to be a T, but true love turns out to be her final weakness - maybe indicating F instead. Finally, about J/P, I'm pretty certain she is a Perceiver. She exploits the possibilities that she gets instead of planning ahead, and she quickly adapts to new developments, all pointing to P. Therefore, I'd probably go with ESFP, but there's an almost equally strong possibility of ENFP.
Inspector Lestrade is definitely an ISTJ - the ever law-abiding person who only grudgingly accepts novel thinkers like Holmes to interfere with his work. I don't think a further explanation is needed. I think it's worth mentioning, though, that ISTJs are among the types that would seem the most annoying in a crime novel, because of their love of rules and systems that would sometimes hamper investigations. Fictional ISTJs are often made much more annoying than they would be in real life, because the heroes, who are almost never ISTJS, have problems with their conservative ways.
Watson's love interest and eventually wife Mary is a blatant ENFJ; a skilled governess with a mild and friendly disposition.
Though he only plays a minor role in the scheme of things, I want to point out that Moriarty's second-in-command and the main antagonist in The Adventure of the Empty House, Sebastian Moran, is an ISTP gone wrong. While I have respect for most ISTPs, Moran exhibits all their worst aspects - an adversion to laws, a tendency to violence, and an unruly temper.
Then, finally, the first supervillain - Professor James Moriarty. Though he never appears in person in the original story, only through narrations by other characters than Watson, he is an obvious INTJ, a type who has come to be associated with supervillains since A.C. Doyle introduced him. He is scheming and ruthless, eerily ever-present, and with little regard for life in general. I'm not saying all INTJs are like this, I generally like them more than most other types, but since he is the prototypical supervillain, I have to type him as such.
This was a long introduction. I'll try to be brief with the modern adaptations.
Guy Richie's films (2009 and onwards):
Holmes (Robert Downey Jr.) returns as an INTP - no explanation needed. Watson (Jude Law) is this time around an ISTJ, neat and overbearing with the more unsystematic Holmes, and more ruthless than his other incarnations. Irene Adler (Rachel McAdams) is a clear ESTP with her thirst for adventure. Lestrade (Eddie Marsan) is once again an ISTJ, Mary (Kelly Reilly) an ENFJ, and Moriarty (Jared Harris) an INTJ. Looking at the non-canonical characters, I'd say Lord Blackwood (Mark Strong), the main antagonist in the first film, is a little difficult to type; it would be very easy to say INTJ, but the more I think about it, his devotion to religion and will to break every rule for a greater cause make me wonder if he might be a very unhealthy INFJ. Simza (Naomi Rapace), Holmes and Watson's companion in the second film, is to me an obvious ISFP, and Mycroft (Stephen Fry) is an even more blatant INTP than in the books.
Sherlock (2010 and onwards):
Benedict Cumberbatch's portrayal of Sherlock (though my clear favourite of the ones mentioned) is a difficult one. This is the only incarnation that strikes me as being a possible INTJ, with his careless arrogance and aversion to almost all interaction with anyone but John. I would say INTx, but because I might be biased from typing every other Holmes as Ps, I'll go with INTJ to break a destructive pattern.
John (Martin Freeman), on the other hand, is an obvious INFJ. He is Sherlock's kinder and more benevolent counterpart, the only person who both tolerates and is tolerated by Holmes. Idealistic and tougher than he looks, he is a good person who tries to bear with eccentricity more than every other character in the series. The Lestrade (Rupert Graves) of this series is for once ISTP, more accepting of Sherlock's quirks than his literary counterpart. The annoying ISTJ role is here played by Anderson (Jonathan Aris), a forensic scientist and non-canon character. There is also the condemning Sergeant Donovan (Vinette Robinson), an ESTJ who despises Sherlock more than anything else. Irene Adler (Lara Pulver) is an ESTP here, mostly depicted as an emotionless dominatrix who plays with people's urges and feelings for the fun of it. There's also the genuinely nice Molly Hooper (Louise Brealy), a pathologist with a crush on Sherlock, who is a clear ENFP, and the sweet old lady Mrs. Hudson (Una Stubbs), a caring - though slightly nosy-neighbourish - landlady who strikes me at once as an ESFJ. For once, we're dealing with a non-INTP Mycroft (co-creator of the show, Mark Gatiss); this version is as INTJ as they come, and is indeed the true mastermind of the series.
This Moriarty (Andrew Scott) is one of the most well-made villains I've ever come across; while initially appearing to be an ENTP, he strikes me more and more as an extremely unhealthy ENFP, with his obsessive fixation on Sherlock that almost borders on a stalker-like affection. A Judger would never draw attention to himself and his criminal activities the way this Moriarty does, nor would he appear to be more of a prankster than a scheming mastermind. I would like to write a lot more about this guy, but I promised to be brief, so I will be.
Elementary (2012 and onwards):
Though this Holmes (Jonny Lee Miller) probably comes closest to A.C. Doyle's canon character, he is apparently an ENTP instead of INTP - this because he is outgoing and aggressive in his pursuit of answers to the riddles he is presented with. Unlike the other Holmes versions, this one is fully aware of the social standards he is expected to follow; he simply ignores them and takes plesure in doing so. His female Watson (Lucy Liu) is an ENFJ - a sober companion with a strong desire to help former drug addicts get their life back. Thomas Gregson (Aidan Quinn), Holmes' contact in the NYPD, seems to me a stereotypical ESTJ - rule-following and strict. Detective Marcus Bell (Jon Michael Hill) is most likely an ESFP, with a fairly pleasant attitude and a down-to-earth view that often conflicts with that of Holmes'. Sebastian Moran shows up in this series as well, though only for one episode - still, long enough for me to peg him as an ISTP once again.
So, if you made it this far: Congratulations, you have survived my ramblings Please comment, I want feedback on this thingy.