Hellhounds

Hell hounds will often physically rip their victims to shred to collect their souls, some more vicious than others. They vary in size, from the as small as a large dog to the size of a small horse. Hellhounds are not restricted by religion. 

Common abilities throughout the species  would include super senses, stamina, strength, determination to follow trail til one of the two dies or are called off by their masters, immortality, and invulnerability. While they will never truly age, they can still be killed. Most holy weapons and charms will  function against them, iron causing severe damage and killing them, while salt will ward them off.