Prolific Female Horror Authors

Female horror authors are not as common as male authors, but they do make an impact and many have influenced current writers today. Stephen King has famously said that he was heavily influenced by Shirley Jackson who wrote The Haunting of Hill House. Jackson focused on Gothic horror and adaptations of her work are still being made today.
One of the big names of the 20th century is Anne Rice. Anne has written over forty books in her time, most focusing on vampires. Some of her books have been made into films, the most famous being Interview With The Vampire. She still writes today.
More recently, Laurell K Hamilton has found fame as a horror writer and she constantly hits bestseller lists.
The most prolific horror writer though has to be Mary Shelley. She spawned an entire genre - science fiction horror with her novel Frankenstein. Not bad for someone trying to come up with a ghost story in a friendly competition amongst friends!
There are many great female writers and it would be impossible to name them all. Who are your favourite female horror writers?