Mary Ellaline Terriss, Lady Hicks (born Mary Ellaline Lewin, 13 April 1871 – 16 June 1971), known professionally as Ellaline Terriss, was a popular British actress and singer, best known for her performances in Edwardian musical comedies. She met and married the actor-producer Seymour Hicks in 1893, and the two collaborated on many projects for the stage and screen.

The daughter of the actor William Terriss, Ellaline made her London stage debut at the age of 16 in Cupid's Messenger at London's Haymarket Theatre. Impressed with her performance, the producer Charles Wyndham gave her a three-year contract, under which she first played Madge in Why Women Weep. In 1892 Terriss starred in Faithful James (by B. C. Stephenson) and the following year she starred in the title role of Cinderella, produced by Henry Irving. She was featured in W. S. Gilbert's His Excellency in 1894, followed the next year by a starring role in the George Edwardes production of the musical The Shop Girl, playing alongside her husband. The next year she starred in another musical hit, The Circus Girl.

In 1897, her father was murdered by a deranged actor. As a result, she received much public sympathy, returning to the stage to star in A Runaway Girl in 1898, one of her most successful shows. In the 1900s, she starred in a series of long-running hits, including Bluebell in Fairyland (1901), Quality Street (1902), The Catch of the Season (1905) and The Beauty of Bath (1906). After 1910, Terriss concentrated on comedy roles and music hall tours. Her unsuccessful return to musical comedy, Cash on Delivery (1917), confirmed the wisdom of this new career course.

Her later career also included film roles. She began in the silent films Scrooge and David Garrick (both from 1913) and made a successful transfer to talkies; her last film was The Four Just Men in 1939. She died in Hampstead, England, at the age of 100.