A character who is tsundere displays a quarrelsome and curt attitude in front of others but also has a kind and affectionate nature that is kept hidden most of the time. She or he unwillingly switches between the two character traits, most likely in front of their beloved.
♀-Asuka Langley Soryu (Neon Genesis Evangelion)
♂-England/Arthur Kirkland (Axis Powers Hetalia)
A yandere character is in love on a level of obsession and adopts violent measures to make that person theirs if not even killing them.
♀-Yuno Gasai (Mirai Nikki)
♂-Keisuke (Togainu no Chi- mostly in the game)
A character which is kuudere acts cynically and indifferently towards others but he/she is actually caring at heart. This side is only shown occasionally though.
♀-C.C. (Code Geass)
♂-Byakuya Kuchiki (Bleach)
As opposed to the kuudere, a dandere character is shy and quiet with a caring and kind nature that is kept hidden inside the person. A passionate or affectionate behaviour is seldom.
♀-Yuki Nagato (The Melancholy of Haruhi Suzumiya)
♂-Takashi Morinozuka (Ouran High School Host Club)
Take an anime character of any kind and form a diminutive.
The Chibi is the personification of little and cute.
Usually the head is oversized, the voice is childlike and innocent and the chibi is constantly accompanied by a pink, sparkling or blooming background. In some cases many characters also turn into a chibi for a short humorous sequence.
While Gakuran is actually just the word of 'school uniform' it has become an overall expression for male anime characters in their high school days in which they were/are wearing the most differing school uniforms. The standard form is the black top with a standing collar and matching trousers.
Example: Izaya Orihara and Shizuo Heiwajima
[The girls uniform is the "Sêrâ-Fuku セーラー服 (Sailor Oufit)" that is held in a naval style in its original form.]
Example: Anri Sonohara
Iinchou 委員長 (Class Representative)
The Class Rep, usually not called by anything else but the name 'Iinchou' anymore, cares a ridiculous amount about school and class; interfering in the students' affairs trying to encourage them to make an effort.
Example: Kaname Chidori
Mahou Shoujo 魔法少女 (Magical Girl)
Girls of any age possessing some magical powers which give them new abilities, most likely to save the world from evil or the like. In most cases these girls undergo a glamorous transformation that takes up about 5 minutes of a 25 min. episode and lets them become all sparkly and colourful, often accompanied by various transformation phrases.
Example: Sakura Kinomoto
The Maid, which is usually young and beautiful, is passionately serving her master, 8 out of 10 with a submissive attitude. With her maid outift and the fitting bow in her hair she's one popular object of 'Moe' and almost always existing for the fanservice.
Example: Sayaka Dejima
A shrine maiden in the Shinto religion that in Anime usually helps out there or is related to the owner.
Mostly a character associated with possessing mystical powers that can possibly fight of demons or the like.
And some people consider these Miko outfits as their very own fanservice as well.
Nekomusume 猫娘 (Cat Girl)
A human female with cat ears and optionally a cat tail.
Traits of a cat must not neccessarily be adopted by the character since the ears are mainly additional sources of 'Moe'. But in certain cases the ears can also have a meaning and reason to be there.
Example: Ichigo Momomiya
Ninja (忍者)/ Shinobi (忍び)
The warrior in the shadows, possessing all kinds of mysterious powers like creating doppelgängers and becoming invisible. General weaponry should always contain Shuriken (throwing stars) and Kunai (throwing knife). His creed of showing "no pain or emotion" isn't accurate in all cases of modern Anime Ninja (e.g. Naruto *ahem*) and the traditional apparel of black suit and mask has also been newly interpreted various times. The female form is called Kunoichi くノ一.
Example: Black Star
The 'Young Lady' is usually a female student from a wealthy, high-class family that is demonstrating her superiority amongst the other students. In most cases she has a quite sadistic attitude and is accompanied by a butler or maid shouting "Oujou-sama!", "Oujou-san!" or "Oujou-chan!" after her at all times. Furthermore she's the ultimate object of idolization.
Example: Kanade Suzutsuki
The term for an extreme, passionate geek, especially concerning Anime, Manga and Video Games. Most of this person's life is commited to obsessively engage in his or her hobbies and acquiring and almost unhealthy amount of knowledge on the chosen topic.
Example: Konata Izumi
Easily said the most popular student(s) in school.
Those tend to be unimaginably talented or beautiful, are adored, become dedicatees of fanclubs and seem unreachable. Often that idol is the as previously mentioned Ojou.
Example: Yuujiro Shihoudani, Mikoto Yutaka, Toru Kouno
The Seme is the dominant, 'top' part in a BL aka Shounen-Ai relationship. He is usually the more masculine, aggressive, serious or dark person and taller as well. The Seme often is the pursuer and the only one that manages to mess with the uke's head.
Example: Akihiko Usami
Sensei-chan is a teacher that gets along with the students like they were her friends. Unmarried, young, childish, probably not the highest authority in school and very responsive.
Example: Sawako Yamanaka
An underage boy that is either seen as the icon of moe and cuteness or is portrayed in an erotic manner. Actually quite the same as a lolicon, only of the opposite gender.
Example: Mitsukuni Haninozuka
The Uke is the Seme's counterpart and the submissive, 'bottom' part in a BL aka Shounen-Ai relationship.
The common Uke is often smaller, more emotional and insecure and has more female features. The uke is mostly the only one being able to win the Seme's heart.
Example: Ritsu Onodera