Well, this turned out to be harder to answer than I thought. Eventually I came up with this character:
![Image](https://s1.zerochan.net/Genjyo.Sanzo.600.61854.jpg)
Genjo Sanzo, "the 31st of China" (To give his full title) is a Sanzo Priest, a high ranking Buddhist priest in the world of "Gensoumaden Saiyuki". He is the protector of one of the "Sutras from the Dawn of Time", specifically the "Maten Sutra", a scripture that takes the form of a scroll that is part of a fundamental element in the creation of the universe in the Saiyuki canon. The reason I mention Genjo Sanzo is because despite being a Buddhist priest, he does everything almost counter to their belief system. He is impatient, has a short fuse and is blunt and rude. And he leaves a high body count in his wake. Granted most of those he kills tends to be Youkai who are suffering negative effects from experiments by the main villains in the Anime, as opposed to Humans. But he does kill a lot of Youkai in his parties attempts to complete their mission to reach the West. I don't have an official figure for how many he has killed in the course of his mission but one of the episodes of the later season, "Saiyuki Reload", touch on the fact that to become a Youkai yourself, you must kill a thousand and Sanzo's companions toy with the idea that Sanzo is already a Youkai himself due to the high body count he has left behind. He is an interesting character whose actions arguably go against the very religion he is supposed to be serving, especially in the high numbers of Youkai and occasional bad egg human he kills.
Honorable Mention goes to Jubei Kibagami:
![Image](https://vignette.wikia.nocookie.net/ninjascroll/images/8/8a/Jubei_Kibagami.jpg/revision/latest?cb=20130517103412)
He is a Vagabond Ninja from Ninja Scroll, who despite his lifestyle has a strong moral sense of right and wrong. He kills a lot of the main antagonists of the movie, the "Eight Devils of Kimon". At least 6 kills can be attributed to Jubei if the wikipedia article is correct.
![Wink ;)](./images/smilies/icon_e_wink.gif)