THE ENDER DRAGON!!!!!!!!

O.M.G the ender dragon drops infinity experience points and rarely drops a ender dragon egg!!!!!!!!!!!!

the wither

the wither, the wither is a very power full creature. 1 SINGLE HIT YOUR DEAD!!!!!! the wither very rarely drops a single  wither star.

the Blaze

The blaze,the blaze is a powerful creature, being abel to shoot flame balls at rapid speeds!! 2 hits by a flame ball you're dead!!

the ghast

The ghast, the ghast can kill you by shooting fire balls at you. You can kill it by rebounding the balls back at it.

the skeleton

the skeleton, the skeleton is powerful because of its bow. the skeleton can also put on armour.                                          

the spider

the spider, the spider is quite powerful in strength and drops very useful string that you use to make wool, bows, and fishing rods.

zombie

The zombie, the zombie is quite easy to kill and drops raw flesh.