Cassandra Clare Judith Lewis, better known by her pen name Cassandra Clare, is an American author of young adult fiction, best known for her bestselling series The Mortal Instruments. Authored Books Lady Midnight Author: Cassandra Clare Publisher: Simon and Schuster Shadowhunters Julian and Emma are parabatai. They are allowed to do absolutely everything together except fall in love. City of Bones Author: Cassandra Clare Publisher: Walker Books When Clary visits a nightclub, she discovers that she is one of the Shadowhunters - a group of demon-hunters living in a world of vampires, werewolves and warlocks. City of Ashes Author: Cassandra Clare Publisher: Walker Books In the second installment of the Mortal Instruments series, Clary finds herself falling deeper into New York City's underworld of demons, werewolves, vampires and Shadowhunters.