I'm going to have to go with a comic book which has never been released in English, adapting the stories of an author whose work is also mostly only available in Japanese. Sorry about that.
I was browsing through a local bookstore recently and found a comic book called purporting to be an anthology adapting the various stories of Edogawa Rampo, the father of Japanese mystery fiction. Now, I'm a big Edogawa Rampo fan. I own his complete works (30 volumes and more than 20,000 pages) and I'm even writing my thesis on his work. So, naturally, I decided to pick this comic book up and take a look (Japanese comics are always shrink-wrapped in stores, so I had to by the thing before I knew what it was like).
Now, Edogawa Rampo's most famous character is his "great detective" Kogorou Akechi (think of him as Japan's Sherlock Holmes). The comic adaptation is actually fairly faithful to the plots of Rampo's stories (although it adds a lot of sex), but the character of Kogorou Akechi couldn't be more wrong if they tried. The books describe him as a thin man with tousled hair, not conventionally handsome, but with an intelligent face and a certain charm about him. In this comic he is drawn with incredibly pale skin, sharp, effeminate features and what appears to be a significant quantity of black lipstick and mascara. His hair is disheveled, but its the kind of disheveled you pay three hundred bucks for at a fancy salon.
The Akechi in the books always speaks politely and humbly, although often with some bite to his remarks. The comic changes the sentence endings and personal pronouns he uses to sound more conventionally rough and masculine and has him constantly declaring himself "the greatest detective of the age".
They comic book version is also into BDSM. Akechi was never as asexual as Holmes (he even got married and adopted a child sidekick later on. His boy assistant was a precocious orphan with acrobatic abilities, so he beat Batman to the punch on that one), but when Rampo described him as "a man of strange passions", he was referring to Akechi's interest in Mathematics.
The differences between the original and the adaptation are so many and glaring that it almost comes off as a joke.