The horror genre lends itself to the setup-punchline structure of the limerick, so I wrote a few.
A young looking fellow from Leith
Had very sharp, shiny white teeth
You might get a fright
If you met him at night
And never again will you breathe.
A ragged wee laddie called Fed
Grew lesions that started to spread
His brain liquified
And poor Freddie died
So dead Fred’s head’s spread on Fred’s bed.
The ancient Old One called Cthulhu
Had slept for an eon or two
He woke up last year
Filled men’s hearts with fear
And caused quite a hullabaloo.
A sweet little girl from Dunoon
Grew fur and teeth every full moon
She woke up at dawn
Her family gone
Though bits of them round her were strewn.
A thin, starving flesh-eating ghoul
Picked up his wee brother from school
Then he started nibbling
His unfortunate sibling
Until he was happily full.