Them, or The Xhadows, is/are an Alien race so evil, that even the devil himself does not speak their real name. Them is just one of the many names for the creatures that exist in the MV-Mythos universe. They are not physical beings and are not based on matter.
Superhuman Strength: Are much stronger than any Human. They can shatter metal, snap handcuff links, overpower/kill Humans in may ways with ease, lift and throw heavy objects (motor cycles, pool tables, and giant creatures) high in the air and across long distance, smash metal, weild large weapons, break the jaws of a Dragon, and demolish building complexes. Some can even shatter worlds.
Superhuman Durability: Are virtually invunerable to attack.
Superhuman Agility, Speed & Reflexes: A Xhadow can easily dodge bullets
Animal and Creature control
Biokenisis/Genetic Control or Reanimation
Psychic Vampiric tendencies
Dimmensional Barrier Control and Teleportation
Colossal Fear Projection
Life and Matter Creation
Body-Part Reconnection and Control
Psionic Energy beams
Life & Matter Transmutation
Cosmic-Level Energy & Matter Manipulation and Absorption
Psionic Force-Field Projection
Master of Magic and Technology
and several other powers like phasing through walls.
It is near impossible to defeat them, though certain aspects in time can drive them away.