Claiming number one in first post! The Black Mamba! I met one once before and another time one went into hotel kitchen where friends where staying. Things are mental aggressive with no comprehension of fear or self preservation when it encounters creatures in the wild it perceives as threats...and that's almost anything that moves.

Stats:

>18km per hour land speed
>Longest and fastest snake in Africa
>20min for poison to kill a human
>100% kill ratio for centuries as anti-venom wasn't developed until recently
>It can raise half it's body up in to the air and is excellent at reaching up trees.