I don't think there has been any post done here yet which actually types all the Death Note characters.
I love this show and watched all 37 episodes in less than a week.
This show has some great examples of Rationals- the creators of Death Note are likely NT themselves. There are some characters I am still 50/50 on.
Yagami Light-ENTJ (I've heard INTJ but given his 'god complex' and ways of dealing with people- you see more of a power-hungry, highly intelligent, and charismatic ENTJ than an INTJ. An extravert doesn't have to be a lover of people- especially an Extraverted Rational).
L-INTP (What else could he be?)
Near-INTJ (Seemed more confident in his deductions but less precise than L)
Mello-ENFP (Despite his extremely high intelligence, one of his problems was that he let his emotions control what he did- only in the way that XNFP types let them do. I could see ENTP or even ENTJ.. but Mello's Fi is definitely stronger than his Fe and if he was ENTJ that would make Fi his inferior function which it is definitely not.)
Chief Yagami-ISXJ (Seemed very T towards the beginning but got more F-ish later on, I'm leaning towards ISTJ though, I don't think an F would berate himself as much for 'acting on his emotions'.)
Matsuda- ESFP (What else? Impulsive and often served as comic relief.)
Teru Mikami- ISTJ (A serious Guardian who was in love with justice)
Ryuk- ENTP (He hates boredom and loves apples.. both lead me to say ENTP.)
Misa Misa- ENFP (In love with Light only in a way that an ENFP could do so.)
Mogi- ISTJ (A quiet and cautious type who was devoted to the Kira case. I used to think ISFJ but his enthusiasm as Misa's manager seemed way too overdone and planned for an F type. I've seen ultra enthusiastic ISFJs before and they are actually crazy, )
Aaizawa- ESTJ (Assertive and his strong Te led him to the obvious conclusion that Light has to be Kira and he never seemed to stop believing it after the '13 day rule' proved to be fake).
Watari- INFJ (L's loyal partner- played an SJ-ish role without seeming SJ-ish in terms of personality. His devotion to helping gifted children develop their strengths suggests a strong NF type).
Takada- ESFJ (Her love for Kira was similar to that of Teru Mikami but she had a much warmer personality and unlike Teru could never get herself to actually use the Death Note)
Rem- INFP (She sacrificed herself in the end to save the life of Misa, even though, she seemed to have a good idea of what would happen from the very beginning.. she never took much of an assertive stance against the humans, which suggests INFP. Ryuk's reasons for letting Light do what he desired were very different than why Rem let things go on).
Anyone disagree with my typings?