Helen Vendler, one of the most influential literary critics of her time, died Tuesday at 90. Vendler, who taught at Harvard University for many years, was known for her insightful readings of poetry and her ability to help poets understand their own work. She was also a prolific writer, publishing over 30 books of poetry criticism and essays. Vendler’s work has had a profound impact on the field of poetry, and she will be deeply missed by her colleagues, students, and readers.