Eliza Doolittle is a fictional character who appears in the play Pygmalion and the musical version of that play My Fair Lady. Julie Andrews originated the musical version of Doolittle on stage in My Fair Lady, with Rex Harrison as Professor Higgins.

Andrews' performance served as the definitive portrayal until Audrey Hepburn played the role in the highly successful 1964 film musical My Fair Lady.

Audrey Hepburn apparently believed that Julie Andrews should have played Eliza Doolittle in the film, but was told by Jack L. Warner that Julie wouldn't be cast even if Audrey turned the role down. Julie Andrews said that she "threw a few tantrums" when she learned that she wouldn't be playing Eliza in the film, and yet, she got along very well with Audrey Hepburn, without holding a grudge against Audrey whom she knew was an innocent party in the whole thing.

More Info: en.wikipedia.org