Maybe it’s just me, but I can’t help but see similarities between the characters in Batman and in Sherlock.
 
Sherlock Holmes – Batman/ Bruce Wayne: I sometimes think that ACD’s Sherlock Holmes was an influence on Bob Kane when he created him in the 1930’s. Unlike all other superheroes, Batman does not have any super powers but rather a super intelligent mind just like Sherlock Holmes. At his core he too is a detective that uses his skills to solve crimes and fight enemies. Both of them have strong knowledge of science, chemistry, and forensics. They also both represent the dark side of genius as neither one of them is sentimental and at times can be morally grey (as Sherlock says “I might be on the side of the angels but don’t think I’m one of them”).
 
John Watson - Robin/Dick Grayson: It is true that Watson is certainly not a young boy or teenager like Robin but he makes the perfect foil to Sherlock just as Robin does to Batman. Robin can be in awe of Batmans discoveries and conclusions just like Watson is with Sherlock’s. While they both can be naïve and occasionally short-sighted, they can hold their own and are trustworthy companions. All in all, they both share and earn the title of “sidekick.”
 
Lestrade - Commisioner Gordon: Just as Gordon is Batman’s closest ally in the Gotham City Police Force, the same can be said for Scotland Yard’s Inspector Lestrade for Sherlock. They both rely on the expertise of Batman and Holmes to help them solve crimes and catch criminals. Not to mention that they both put their faith in them even when everyone else on the division doesn’t.
 
Irene Adler - Catwoman: Both are rogue female figures that are both criminal but not exactly evil. They can ally themselves with villains (like the way that Irene had known Moriarty) but they always have their own interests at heart. They both use their sexuality to their advantage. Just as Irene had tried to seduce Sherlock, Catwoman does it all the time with Batman. Plus, Catwoman has outsmarted Batman before just like Irene had with Sherlock. It can also be said that the personal bond between Batman/Catwoman and Sherlock/Irene is similar as they both are fascinated by each others wits and intelligence.
 
Jim Moriarty - The Riddler and The Joker: As we see in TGG, Moriarty loves to play games and leave puzzles for Sherlock like The Riddler does for Batman. It is probably boredom that drives The Riddler just like it drives Moriarty. Also as we see in TRF, Moriarty is an ingenious psychopath just like The Joker as they have both orchestrate creative ways to destroy our heroes. Moriarty might not laugh like The Joker does but he does have a childish nature to him as if he is some kind of clown. Both Andrew Scott’s Moriarty and Heath Ledger’s Joker in 2008’s The Dark Knight are brilliant and alike because they both capture sick people with a manic nature that is hard to describe particularly in their voice tones and speech style. Ledger’s Joker thrived on anarchy but I think Scott’s Moriarty had this in mind as well. “Did you miss me” is just as memorable as “Why so serious?”
 
Charles Augustus Magnussen - Ra’s Al Ghul: In the comics, Ra’s is the head of a criminal empire just like Magnussen was the head of a media empire. Both are wealthy and are considered untouchable. Like Magnussen, Ra’s can be “a necessary evil” to foreign governments even though his quest for more power is dangerous. The revelation of Magnussen’s mind palace in which he supposedly knows everything suggests something supernatural even it is likely something natural, in which case it bares resemblance to the parlor tricks that Ra’s likes play in his battles with Batman (particularly his constant resurrections).