Lillah McCarthy (22 September 1875 – 15 April 1960) was an English actress and theatrical manager.
McCarthy was born in Cheltenham. She studied elocution under Hermann Vezin and Emil Behnke, and made her first appearance on the stage in 1895. She joined Wilson Barrett at the Lyric, London, in 1896-97, and after touring in Australia in the same company as her brother Daniel, and Maud Jeffries, she became leading lady with him in 1900, playing in Quo Vadis?, The Sign of the Cross, Knowles's Virginius, Hamlet, and Othello. She then accompanied Barrett to South Africa and Australia. In 1904 she played with Beerbohm Tree at His Majesty's Theatre in the adaptation Agatha by Mrs Humphrey Ward and Louis N. Parker from her 1903 novel, Robert Buchanan's A Man's Shadow, and Julius Cæsar. Subsequently she appeared in Man and Superman (1905); Maurice Hewlett's Pan and the Young Shepherd (1906); Arms and the Man (1907); What Every Woman Knows (1908); John Galsworthy's Strife (1909); Maugham's Grace (1910); John Masefield's The Tragedy of Nan (1911); Twelfth Night (1912).