Katrina is a minor character (antagonist) in The Wardstone Chronicles/The Last Apprentice.
Katrina was the witch assassin of an Essex witch clan. Much of her history is unknown. Katrina wore the shrunken skulls of her slain enemies as earrings. They had the appearance of golden orbs. It is known that Katrina and Grimalkin have heard of each other before, as Katrina taunts Grimalkin by saying "Fools have whispered your name in the dark, and put forth vaunted lies about you", and Grimalkin tells Tom that she and Katrina have never met before. Katrina leads a group of hundreds of witches and abhumans while 4 abhumans carry the Fiend's coffin through Wales. She later taunts Grimalkin at the Battle of the Wardstone, as Tom Ward's forces are halted by a powerful spell. Grimalkin and Katrina then fight, with Katrina being slain by Grimalkin as the first casualty of the Battle of the Wardstone.