King Fuzzy (also known as Giga Fuzzy) is the leader of the Fuzzies and the first boss that Mario and co. encounter. It is the boss of Yoshi's Island, fought in Timber Tower and Creepcrack Castle. It appeared to be a regular Fuzzy until Kamek used his magic on it.
King Fuzzy looks exactly like a Mega Fuzzy in terms of features, very hairy. It is about 3 or 4 times larger than that of a Fuzzy.
Giga Fuzzy simply jumps across the room. There are platforms above Mario with Violet Blocks that he can use to damage it. Hammers are also effective. After being hit, Giga Fuzzy will roll around the room, eventually going back to its jumping state. Repeat this process about 2 more times and it will be defeated.