Conversation so far:
What was the first film that Rex Harrison starred in?
Harrison's film debut was in The Great Game.
Was is considered to be a success?
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He was best known for his portrayal of Professor Henry Higgins in the 1964 film version of My Fair Lady.
Did this film do well with critics?
CANNOTANSWER.
Did he act in any other films?
He also starred in 1967's Doctor Dolittle.

Question: Who did he act with?
Self-contained rewrite: Who did Rex Harrison act 1967's Doctor Dolittle with?