clipped from: www.cracked.com   
#10.
The Wallmasters from The Legend of Zelda: Ocarina of Time
#9.
The Poltergeist from Splatterhouse

#8.
The Dog from Paperboy
#7.
The "Polygon Monster" from Out of This World


wtf.

#6.
The Cherub from Doom 3

clipped from: www.cracked.com   
#5.
Baron von Blubba from Bubble Bobble

#4.
Any Body of Water from Sonic the Hedgehog 2

#3.
Sinistar from Sinistar

#2.
The Poison Head Crabs from Half Life 2

#1.
Evil Otto from Berzerk

Our number one villain is unstoppable, immortal and can be easily drawn on MS Paint. He's Evil Otto, the scariest face in gaming history.

It was Otto's job to fly through the poisonous walls and zap you when the timer ran low. Otto was merely a pain, but what makes him truly frightful is the fact that he is possibly the only video game enemy in history to kill players in real-life. Between 1981 and 1982, two teenage Berzerk players died of heart attacks shortly after posting high scores at video arcades. Evil Otto watched them die ... with a smile on his face.