One step closer!
As with heroes, anime has provided us with many fine villains.The pitiless and powerful Arago-sama (aka "Lord Talpa") from Yoroiden Samurai Troopers, the incomparably powerful Cell from Dragonball Z (and the completely insane Freezer-sama from the same anime), Dante and Father from Fullmetal Alchemist (the original and Brotherhood, respectively), Vega-Sama (aka "M. Bison") from Street Fighter II: The Movie,, Kagato from Tenchi Muyo!, Franken Von Fogler(1) from Giant Robo, Yakumo from YuuYuu Hakusho, the fanatical Alexander Anderson from Hellsing, the arrogant and devious Count Cagliostro from The Castle of Cagliostro, the list goes on.
However, despite starting to sound like a broken record, my answer ultimately has to be the "gentleman", and I use the term VERY loosely, in my icon: Orochimaru from Naruto/Naruto Shippuden.
This is the man that Lord Voldemort would have WANTED to be, but had neither the intelligence, skill, or deviousness to match. This is a man who started out as one of three great heroes but had the terrible flaw that he was, when all was said and done, a sociopath. At first a well-socialized one for his world, he became obsessed with achieving the ultimate in skill so that he could literally defeat death -- according to one source, originally for the sake of Tsunade, the woman who trained alongside him and Juraiya when the three became the legendary Sannin of the Leaf. But he delved into the forbidden techniques of the shinobi with a terrifyingly methodical scientific approach and absolutely no conscience, and in the end became a complete monster of such terrible capabilities that he, alone, was a threat to entire villages of well-trained shinobi. To prolong his life and increase his power he found a way to transfer himself to different bodies, burning up their lifeforce as casually as others might wear out a suit of clothing, then shedding them as a snake sheds its skin -- literally, for Orochimaru also has given himself many snakelike traits, perhaps stemming originally from a quest to gain some of the reptilian powers of healing but now more a tool of terror. There are virtually no techniques he has not mastered, and he is a man capable of taking a very long view of things, planning events and moves years ahead -- a master of the Xanatos Gambit. He is so good at surviving that I am not yet convinced he is truly dead despite certain events in the anime and manga; the powers his former right-hand man and best student Kabuto is showing are ones Kabuto CLAIMS to control... but I would be totally unsurprised to find out that they're simply a surviving piece of Orochimaru which will eventually claim Kabuto as he has claimed so many others.
Frightening, powerful, deadly, brilliant. Orochimaru.
Day 1 - Very first anime:Saint Seiya
Day 2 - Favourite TV series: : The Vision of Escaflowne
Day 3 - Your anime crush: Belldandy, from Ah! Megamisama/Ah/Oh My Goddess! and Shun from Saint Seiya
Day 4 - Favourite Film: Tonari no Totoro/ My Neighbor Totoro
Day 5 - Anime character you feel you are most like (or wish you were): Shikamaru from Naruto Shippuden
Day 6 - Most annoying anime character: Mihoshi, Tenchi Muyo!
Day 7 - Character you’d most like to slap: Sasuke, Naruto Shippuden
Day 8 - Most epic scene ever: End battle of YuuYuu Hakusho: The Poltergeist Report Movie
Day 9 - Saddest anime scene: Belldandy erasing herself from Keiichi's life in Ah! Megamisama/Ah/Oh My Goddess!
Day 10 - Favorite slice of life anime: Koko wa Greenwood
Day 11 - Favorite mech series: Giant Robo: The Day The Earth Stood Still
Day 12 - Best instalment of a franchise you don’t like: Nihao My Concubine
Day 13 - Worst instalment of a franchise you do like. Dragonball GT
Day 14 - Current (or most recent) anime wallpaper: Picture of Son Goku with Shen-Long done by my wife Kathleen
Day 15 - A reality check for a genre you like : Power-warrior anime and internal sanity/consistency!
Day 16 - An anime classic that simply doesn’t work for you: Neon Genesis Evanjellydonut... er, Televangelist...er, Evangelion
Day 17 - Best Background Music: Giant Robo: The Day The Earth Stood Still
Day 18 - Best Five-team: Yoroiden Samurai Troopers/Ronin Warriors (no link, too expensive)
Day 19 - Change you’d like to make to any one anime: Specific Change: Eliminate one nasty action from the history of Juraia-sama in Naruto/Naruto Shippuden. General Change: Eliminate the Saiyajin focus and expand capabilities and screen time for all major characters in Dragonball Z.
Day 20 - Most ambiguous anime character: Selected Maraich and Patalliro, from Patalliro!
Day 21 – Favourite OAV Series : Except for two I've already mentioned, Bastard!!
Day 22 - Animation studio you'd most like to slap: Gainax, for Neon Genesis Evangelion
Day 23 - Anime you think had the best, or most intriguing art: The Five Star Stories
Day 24 - Favorite anime hero or heroine: Uzumaki Naruto from Naruto Shippuden
Day 25 - Best anime villain: Orochimaru, Naruto Shippuden
Day 26 - Your favorite harem anime
Day 27 - Favorite anime opening theme song
Day 28 - Favorite anime companion/summoned creature
Day 29 - Best Anime Music Video
Day 30 - Favorite anime ending theme