Isabel Emily Jay (17 October 1879 – 26 February 1927) was an English opera singer and actress, best known for her performances in soprano roles of the Savoy Operas with the D'Oyly Carte Opera Company and in Edwardian musical comedies. During Jay's career, picture postcards were immensely popular, and Jay was photographed for over 400 different postcards.
After studying at the Royal Academy of Music, Jay joined the D'Oyly Carte Opera Company in 1897, with whom she began singing principal roles immediately, becoming the company's leading soprano in 1899, where she played leading roles in comic operas including The Rose of Persia, The Pirates of Penzance, Patience, The Emerald Isle and Iolanthe. She married and left the company in 1902. She returned to the West End stage in 1903 and starred in eleven musicals over the ensuing years, including A Country Girl, The Cingalee, Véronique, The White Chrysanthemum, The Girl Behind the Counter, Miss Hook of Holland, King of Cadonia and The Balkan Princess. She retired in 1911 at age 31.
Jay was born in Wandsworth, London, the youngest child of John Wimburn Jay, an insurance officer, and his wife Isabelle Clara (Wicks). She was the great-granddaughter of John George Henry Jay (1770–1849), a musician and composer connected with the Royal Academy of Music. She began to sing in public at the age of twelve. She entered the Royal Academy of Music in 1895, where she studied piano and voice. In 1897, she was the first winner of the Gilbert R. Betjemann gold medal for operatic singing. While still at the Academy, she drew the attention of Helen Carte.