Grendelkin

The Grendelkin is a monster. It first appears in the short story "Heorot".

Description
It is decendant of Grendel, one of the monsters from the Anglo-Saxon epic poem Beowulf.

It is covered head to toe in hair, weighing over a quarter of a ton, with fangs, long black finger nails, and black blood. The Grendelkin is both strong and fast, and can use limited veiling magic to sneak up on prey. It eats humans, but also requires them (specifically virgins) to reproduce.

Something in mead makes Grendelkin fertile. Once it gets spawn upon a woman the grendelkin baby bursts from the mother, killing her.

The Grendelkin has the ability to counterspell magic, making him a deadly opponent to wizards. In "Heorot", it was implied that this ability is not shared by all Grendelkin but is unique to the specific one in the story.

"Heorot"
In "Heorot", McAnally asks Harry Dresden to help Roger Braddock get his newlywed wife, Elizabeth, back after Grendelkin abducts her from Loon Island Pub where a brewing competition is being held. Harry and Gard team up to rescue Elizabeth Braddock since she is hunting Grendelkin. They encounter malks along the way.