Judith Lewis, writing under the pen name Cassandra Clare, is an American author celebrated for her young adult fiction. Born Judith Rumelt in Iran to American parents, she spent her childhood traveling extensively before settling in California and later New York City, where she worked in entertainment media. Clare's writing career took off with "The Mortal Instruments," a bestselling series that launched in 2007 and has since expanded into a sprawling universe known as the Shadowhunter Chronicles. This universe includes multiple interconnected series, prequels, and companion novels, exploring themes of urban fantasy and the supernatural.

Clare's work has achieved significant commercial success, with "The Mortal Instruments" series being adapted into a film and television show. However, her career has also been marked by accusations of plagiarism stemming from her early fan fiction work and a lawsuit from another author over alleged similarities in their series. Despite these controversies, Clare has continued to produce numerous bestselling titles within the Shadowhunter universe, solidifying her position as a prominent figure in young adult literature. She currently resides in Massachusetts.

Cassandra Clare is most recognized for creating the extensive "Shadowhunter Chronicles" universe, which began with "The Mortal Instruments" series. This universe is set in a hidden world populated by half-angel demon hunters known as Shadowhunters, who protect humanity from supernatural threats. The original "Mortal Instruments" series, starting with "City of Bones," follows a group of young Shadowhunters in contemporary New York. Clare has since expanded this world significantly, introducing prequel series like "The Infernal Devices," set in Victorian London, and "The Last Hours," also set in the past. Further contemporary series, "The Dark Artifices" and "The Eldest Curses," continue to explore different facets and characters within this interconnected narrative. The universe also includes numerous companion books, short story collections, and graphic novels, all contributing to a rich tapestry of lore and character development.

Clare's writing often centers on themes of identity, family, love, and the struggle between good and evil, typically within a contemporary urban fantasy setting. Her narratives frequently feature intricate plots, romantic subplots, and a large cast of characters navigating complex relationships and dangerous supernatural conflicts. The Shadowhunter universe blends elements of magic, mythology, and demonology with the modern world, creating a unique blend that resonates with a young adult audience. Her works are characterized by fast-paced action and a focus on the emotional journeys of her protagonists as they discover their powers and confront dark forces.

Cassandra Clare's career has faced scrutiny due to plagiarism accusations. These allegations primarily relate to her early fan fiction writing, particularly "The Draco Trilogy," where she was accused of copying substantial portions from other works without attribution. These accusations led to her being banned from FanFiction.Net. Later, author Sherrilyn Kenyon filed a lawsuit claiming Clare's "Shadowhunters" series infringed on Kenyon's "Dark-Hunters" series. Although Clare's legal team stated she had not read Kenyon's books, the lawsuit was eventually settled out of court, with Kenyon later removing the core copyright violation claims. These controversies have been a significant aspect of public discussion surrounding Clare's work.