Zombie

One of the most classic mobs from minecraft, this green boy has wormed his way into the pocket edition, as the first hostile mob.

general info
Because of the lack of real information, the zombie's HP is quite unknown. However, the sword in PE takes two hits to kill the mob, the axe, three, the pickaxe, five. Also, the lack of any other hostile mob makes this creature spawn en masse, making it a formidable enemy currently, as up to ten may ambush you at once.

Strategies
one common strategy currently is to "torch out" (a term in PE referring to the over use of the infinite torches) and then make them not spawn at all.