Cassandra Clare is an American author best known for her young adult fantasy series, including the popular The Mortal Instruments. Born on July 27, 1973, in Tehran, Iran, she grew up in various countries before settling in the United States. Clare began her writing career in fan fiction before transitioning to original works. Her books often feature themes of love, friendship, and the battle between good and evil, set in richly imagined worlds. In addition to The Mortal Instruments, she has written several spin-off series, such as The Infernal Devices and The Dark Artifices, which have garnered a large following.