Helen Carte Boulter (born Susan Helen Couper Black; 12 May 1852 – 5 May 1913), also known as Helen Lenoir, was a Scottish businesswoman known for her diplomatic skills and grasp of detail. Beginning as his secretary, and later marrying, impresario and hotelier Richard D'Oyly Carte, she is best remembered for her stewardship of the D'Oyly Carte Opera Company and Savoy Hotel from the end of the 19th century into the early 20th century.
Born in Wigtown, Scotland, she attended the University of London from 1871 to 1874 and pursued brief teaching and acting careers. In 1877 she obtained employment with Richard D'Oyly Carte and became his assistant and, later, business manager. She helped to produce the Gilbert and Sullivan and other Savoy Operas, beginning with The Sorcerer in 1877 and helped Carte with all his business interests. One of her principal assignments was to superintend arrangements for American productions and tours of the Gilbert and Sullivan operas.
She married Richard in 1888. During the 1890s, with her husband's health declining, Helen assumed increasing responsibility for the businesses, taking full control upon his death in 1901. She remarried in 1902 and continued to own the opera company and run most of the Carte business interests until her death. Although the D'Oyly Carte Opera Company's operations decreased after Richard's death, Helen staged successful repertory seasons in London from 1906 to 1909, establishing that the Gilbert and Sullivan operas could continue to be revived profitably; the company continued to operate continuously until 1982.
By the time of her death in 1913, the opera company had become a repertory touring company. Helen engaged J. M. Gordon to preserve the company's unique style. In her will, she left the Savoy Theatre, the hotel business and the opera company to her stepson, Rupert D'Oyly Carte.