Megumi Hayashibara was chosen to play Rei Ayanami, who became the archetypical Emotionless Girl; at the time, Hayashibara had become famous for her portrayals of Bokukko, Genki Girls, and generally outspoken characters — characters like Asuka Langley Soryuu, basically.
This is also the case in the English dub where Amanda Winn Lee, more known for playing hyperactive Rio in the Burn Up! series, filled the part of Rei.
Interviews from the Rebuild 2.0 Complete Records indicate that the makers deliberately cast voice actors whose voice and image would conflict with the characters, which is why they continued the tradition by having Maaya Sakamoto play the very eccentric Blood Knight Mari Makinami.
The US dub got this as well, with Lelouch being played by Johnny Yong Bosch, best known for being a former Power Ranger, while Suzaku is played by Yuri Lowenthal, best known for playing Sasuke Uchiha. The dub's producers remarked that Taniguchi had a hand in the casting, indicating that he pulled the stunt a second time.
He went further against type in Persona 4, where he plays Tohru Adachi, a seemingly incompetent Butt Monkey of a police detective, which is a far cry from his usual heroic roles. This becomes even more apparent when it turns out that not only is Adachi the killer, he's Ax-Crazy to boot.
While being cast as Izaya Orihara could also be considered Playing Against Type, Johnny's basically established "evil, slimy, and/or manipulative bastard" as his secondary type at this point.
Actually, Bosch has a second secondary type other than playing slimy anti-heroes/villains: the soft spoken/whiny young boys. There are Renton and Claus among quite a few others.
And by Fate/Zero, guess what. He plays as a sociopathic man named Ryuunosuke who loves to see people dying in brutal ways.
Rie Tanaka usually provides voices for peaceful, meek and/or strait-laced heroines like Chii from Chobits, Lacus Clyne and Meer Campbell from the Gundam SEED verse, and Yomi from Azumanga Daioh...but she was also the voice behind at least three devious/brutal villains: Suigintou from Rozen Maiden, Tomoe Marguerite from Mai-Otome, and Liang Qi from Canaan.
And then there's Morganna Mode Gone from DotHackSign...
Her performance as gorgeous exhibitionist high school teacher Yoshimine Mitsuka in DearS, who likes to strip down to her lingerie in front of her students and, at least in the manga version, openly stated that it turned her on to know that teenagers were checking out her body. In fact, she nearly seemed to be having an orgasm when she said that...
Another voice actor which falls into this category is Yuko Goto, most known for her cute-and-vulnerable moe-roles like Mikuru Asahina. She is really a down-to-asphalt motorcycle-devotee and actually voiced her own caricature, the hyper-masculine Yakuza-styled Gotouza, in Lucky Star.
In Lego Batman, there are plenty of characters that are his type, like Batman, The Joker, Two-Face, Killer Croc... except Killer Moth, who's possibly the biggest loser in Gotham, and Blum voiced him too.
In this specific instance, however, Vic originally tried out for the role of Gino Weinberg, a goofy and cheerful character more his type (and he's said that he really wanted the role too). Gino ending up going to Dave Wittenberg while Vic was cast as the psychopathic Luciano Bradley instead.
For that matter, he also played Rom Ro in Heroic Age, who is not only the closest thing the series has to a Big Bad, but is very quiet and pensive.
And let's not forget Vic also voices Greece!
Vic Mignogna also sings some of FUNimation's One Piece openings. He doesn't seem like the singing type.
Vic Mignogna voices E-123 Omega in Sonic the Hedgehog, a 1200-pound robot Anti-Hero who will do whatever it takes to kill Dr. Eggman. He's more difficult to recognize as Omega than most of his other roles.
And one of the villains in the fourth Bleach movie, Shuuren.
Aside from Furuya, many seiyuus of past Gundam protagonists or a Major Supporting character voiced antagonists within the series: namely, Romi Paku (Loran), Kazuki Yao (Judau), Daisuke Namikawa (Al), Tetsu Shiratori (Sai) and Keiji Fujiwara (Eledore). The English version followed suit with the casting of voice actors such as Scott McNeil as Ali Al-Saachez (Duo), Kirby Morrow as Billy (Trowa), Nicole Bouma as Nena (Meyrin), Meryke Hendrikse as Liu Mei (Lunamaria) and Michael Adamwhaite as Ribbons (Yzak).
Possibly the biggest surprise in 00 may have been the casting of Brad Swaile as Setsuna F. Seiei. Swaile was at this point best known for his emotional characters (and yes that includes Light, who while sociopathic is still rather hammy and over the top at points), and the casting of him as the nearly emotionless, traumatised Setsuna was a surprising one. It still worked out pretty well though.
Scott McNeil would later play Antoine from Dead Rising 2, an insane cannibal chef who kidnaps people and cooks them alive to be made into his "special dish" so he can be famous.
Rie Kugimiya, who is commonly known for her Tsundere characters including the "Four Tsundere Wonders" Shana, Louise, Nagi, and Taiga, is often pigeonholed into these types of roles. This just makes the exceptions stand out all the more.
07th Expansion, responsible for the When They Cry series loves to have voice actors do this, especially when casting them in supposedly pigeonholed roles, only for the character's true nature to come out:
Daisuke Ono: Known for playing charming bishounen, has played Mamoru Akasaka and plays stubborn, rebellious, somewhat perverted Battler Ushiromiya.
Rie Kugimiya: Famous for her tsundere little girl roles, plays kind and surprisingly... complexMeido Shannon.
Soichiro Hoshi: Often cast as passive characters who snap. His role, Keiichi Maebara snaps a number of times, but is anything but passive.
The actor who played L in the English dub of Death Note, Allesandro Julliani, had previously mainly voice acted as the Prince Charming equivalents in the Barbie movies. This is really playing against the type when you consider that L is said to be socially awkward and has no luck in romantic areas. Not that L really cares.
Brad Swaile was usually cast as awkward and/or dorky characters, usually teenagers. Then comes the Death Note dub, and he plays Magnificent Bastard main character Light Yagami. This totally works and is generally considered to be his best performance ever.
Plus, Swaile usually plays lead characters, like the afore-mentioned Light Yagami, but in Shakugan no Shana, he was Keisaku Sato, a minor character.
He was also "Slappy" from Dead Rising 2 a giggling delusional lunatic who believed himself to actually be the mascot he was portraying in costume while wielding a pair of flame throwers spraying them in random directions.
AND Shutaro Mendou (Urusei Yatsura's version of Mitaka), and Kazamatsuri from Yawara (a Romantic False Lead again), not to mention Ryo from City Hunter. He did a LOT of romantic rivals/sex maniacs. Some fans think the action hero bit was just a sidelight (he was also Kinnikuman, but no one brings that up)..
Greg Ayres is known for playing innocent young boys or fun loving teenagers, but he has played vastly different characters at least twice first in Fullmetal Alchemist he voiced Bido a former human who has been turned into a lizard chimera who is a con artist and trouble maker, and in Gantz, he voices Hajimeh w Muroto a psychotic teenage serial killer and rapist.
In both Samurai 7 and Nightraid1931, he voices characters who initially seem to fit his fun-loving, easy going type, but are revealed to have Stepford Smiler traits and are actually less nice/more melancholic than you'd expect.
Kenji Utsumi often is the go-guy for voicing rather big characters, yet in the Red Ribbon Army saga of Dragon Ball, he voices the leader of the eponymous villainous army, Commander Red... who is a complete midget. Still met up with the other standard of being a Military dictator, though.
Chris Ayres normally plays deep-voiced characters who are either antagonists, or in the supporting cast who are in middle-age, so it's surprising to see that in Gantz he played Kei Kurono, who's not only a young-teenager-like character, he's also the main character, and this troper can't think of any other show where Chris Ayres plays the lead role.
Karen Strassman usually employs a tremendous amount of feminine grace in her characters, heroines and villainesses alike. But in Hellsing Ultimate, she voiced Heinkel Wolfe and she sounded quite butch.
In the English dub of Linebarrels of Iron, Todd Haberkorn, who generally plays heroes or comic relief characters channels a Ribbons wannabe main villain, who is assisted by a character voiced by Vic Mignogna, who generally (with some exceptions, see above) gets the same kind of casting. In the other direction, Jerry Jewell, who often plays sinister characters, is cast as a cool Nice Guy.
The true against type for her is Princess Emeraude from Magic Knight Rayearth, who is tiny, willowy, super feminine and NOT EVEN TOUGH. That is, until her lover is killed... but even her feminine touch still lived on. The show, however, also has a more in-type role for Megumi Ogata, though: Eagle Vision.
Show Hayami is mostly known to voice characters who appear good but in fact they are evil sociopaths that love playing with people's minds and torturing them like Aizen in Bleach. Yet, he also voices characters completely different from his normal type like Ichiya or Umibozu in Gintama. Or if you want a Crazy Awesome example, there's Klein Sandman.
The most jarring example, however, has got to be a minor role he got in GEAR Fighter Dendoh where he plays Ginga's overly flamboyant father who's EXTREMELY PRONE of broken English. In fact, flamboyant doesn't even begin to describe this character (though only for 1 episode, and Hayami also voiced the Big Bad, who's more in-line of his type)
Yuuki Kaji has both played Shu and Issei in the same season. One is a brooding, angsty guy who is forced to become king, and the other one is a lecherous hotblooded kid who wishes to become the ultimate pawn. You try listening one then go to another. It's pretty amazing that he has two protagonist roles which are polar opposites of each other.
Then comes the next season where he plays Haruyuki, the resident Gonk and subject to lots of bullying almost everyday in Accel World. Personality-wise, he believes he is but trash in the real world and often locks himself up in a virtual world.
Although, considering the heavy subtext of the Precure franchise, you could say the last one MIGHT be a lil' spot on for Nabatame... In fact, the presence of Nabatame turns this particular Precure into 'the most Les Yay-ridden Precure series ever' and the first Precure that got a LesYay page on its own!