Don't know how many have enough information on him to debate, but I've seen it postulated that he's an INFJ, INFP, ENFP, etc. I'm not entirely sold on INFJ, so I'm curious if anyone has an opinion on this. It's quite obvious he has Fe, but I can't say anything else for certain.
The difficulty with typing celebs is that what we see is sometimes/often a doctored image.. Of course, the inverse could be proposed based on (if any) viewpoints he's strongly taken up - an internal moral system, Fi, but he's very open-minded in situations which could make one's moral/perception system uncomfortable, which indicates the 'adaptable' Fe (example: racy and explicit fanart/fanfiction concerning himself and a friend, Martin Freeman, he deemed 'imaginative' and 'impressive' or something along those lines where he praised the fans for dedication, creativity and originality).
It's been argued he's an introvert because he likes libraries, but that's simply a stereotype - I have many extraverted acquaintances who enjoy libraries as well. Also that he's quite exhausted after performances and such, but it's common sense - who wouldn't be tired after an entire workday of acting nonstop? He still has quite a bit of energy even then in dealing with others (example: NYC PBS Q/A session, in which he met with hundreds of fans but still somehow mustered the energy to remain equally charismatic and charming to the end), which leans me towards extravert based on energy usage.
He doesn't seem to make emotion-based decisions (as INFJs are sometimes prone to do, based on their Fe function), but clearly his sentiments affect him to a point. It's also possible that he does, and his emotion-based decisions just happen to be the most logical ones as well.
tl;dr - any thoughts on Benedict Cumberbatch's MBTI type?