The Different 'Deres'

Yandere
A yandere is a cute and friendly person on the outside, but love will make them mad. Afraid that someone else will fall in love with her senpai, she will do anything to protect him. There are two types on yanderes, possessive and obsessive. Possessive yanderes will go so crazy that they will kill their own senpai just so they can't get anyone else. Obsessive yanderes will murder anyone who gets in the way of their senpai.
FUN FACT: The "Yan" comes from the Japanese word yanderu, which means sick. In this case, it means mentally sick.

Kuudere
Kuuderes are calm people. They often speak in a monotone voice. They will never panic if someone else likes their senpai. They are almost never sad, happy, excited, annoyed, angry, ect. Pretty much emotionalness. They are full of emotions on the inside, fearing that letting people see their emotions reveal weakness.
FUN FACT: The "Kuu" comes from the Japanese pronunciation of "cool", as in calm.

Tsundere
Tsunderes are often stuck-up on the outside, but very loving on the outside. Tsunderes get embarrassed frequently due to the fact that they don't know what to do with their romantic feelings. They try to hide the fact that they like someone in a romantic way.
FUN FACT: The "Tsun" comes from the Japanese word "tsuntsun", meaning high and mighty.

Dandere
Danderes are often quiet and silent. They are almost always embarrassed to be sociable. When danderes are befriended, they lose their anti-socialness and become cute and happy.
FUN FACT: The "Dan" comes from the Japanese word "danmari" which means "silence".