Karl Rankl (1 October 1898 – 6 September 1968) was a British conductor and composer who was of Austrian birth. A pupil of the composers Schoenberg and Webern, he conducted at opera houses in Austria, Germany and Czechoslovakia until fleeing from the Nazis and taking refuge in England in 1939.
Rankl was appointed musical director of the newly formed Covent Garden Opera Company in 1946, and built it up from nothing to a level where it attracted some of the best known international opera singers as guest stars. By 1951, performances under guest conductors, such as Erich Kleiber and Sir Thomas Beecham were overshadowing Rankl's work, and he resigned. After five years as conductor of the Scottish National Orchestra, he was appointed musical director of the Elizabethan Theatre Trust's opera company, the forerunner of Opera Australia.
In his last years, Rankl concentrated on composing. Throughout his career he had written a series of symphonies and other works, including an opera. His symphonies were politely received, but did not enter the regular orchestral repertoire. The opera has never been performed.