If by predator you mean any animal...there are numerous single celled animals that prey on and consume other single celled animals.
When we "look" at the smallest things known, we must consider the group of subatomic particles. The tiniest units of matter exist in this quantum mechanical world. As we're still sorting out some things here, it may be hard to be more specific. But let's nominate the electron neutrino, a fundamental particle, as the least massive of the particles in that group.
The smallest element known to man is Hydrogen (H).
an atom
The smallest carnivore in the world is the least weasel (Mustela nivalis). It is a small and agile predator that primarily feeds on small mammals such as mice and voles. They are found in a variety of habitats across Europe, Asia, and North America.
The smallest snow desert is known as the Atacama Desert in Chile.
amoeba
predator
yes it is actually the smallest known to man
Musk Turtle
carnivourous ant :P
Man is the only predator of sharks.
Of course these beautiful, intelligent birds have a predator - man...
man
Great white sharks have no predators exept for man.
The Siberian tiger is an apex predator and has no predators except man.
man
Man