Saiken, the Six Tailed-Beast

Saiken resembles a large, white bipedal slug with stubby arms and feet and looks like this. It has two prominent optical tentacles, eyes, and hole-like openings as a mouth. Saiken's entire body is covered in a slimy substance. Saiken fell into the hands of Kirigakure, the Land of Water and sealed into Utakata. It was revealed that at some point before its appearance, Utakata's master, Harusame, tried and failed to extract Saiken from Utakata intending to save his student from being a living weapon for the village. Utakata, however, having not heard what his master said to him, later came under the assumption after the incident that his master tried to kill him. This failed removal resulted in Utakata transforming into Saiken and killed Harusame. Like all the other Tailed-Beasts, Saiken has a lot of chakra. Saiken is able to emit corrosive substances that are extremely dangerous on contact in the form of a liquid or gas, which was able to burn through the skin of another Tailed-Beast, such as Gyuki. 

Saiken can be really cool when coming to dangerous substances, but if you are the one who is facing it's wrath, it can be scary.