Abnormal

Deviant type titan
The deviant type (also called abnormal ones) are a rare type of titan

who ignores humans and go to important locations to cause big damage.

History
This type of titans displays a strange kind of intelligence, They do not mindlessly attack humans or try to kill them; they simply run away from them and cause damage in important areas---how this type know where to attack is still a mistery as the titans themselves.

After the Colossal Titan's second attack, the titans got inside and the humans forces had to take action. A deviant type appeared running heading for a tunnel stuck of humans that the soldiers couldn't reach until Mikasa appeared and killed it before he got to the people. Almost all the soldiers from the walls went beyond the walls to find Eren´s house, but in the way a deviant type suddenly appeared running. Armin and another soldier are forced to fight him cutting his tendons of his foot making him fall and stabbing it on the neck.