Robert Orr Chipperfield was a pen name of the American mystery writer Isabel Egenton Ostrander (1883–1924). Born in New York City to Thomas E. Ostrander and Harriet Elizabeth Bradbrook, she came from a distinguished lineage that traced back to seventeenth-century Kingston, New York. Ostrander married songwriter Arthur J. Lamb in June 1907, but they divorced less than a year later.

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Ostrander’s stories were published from 1911 onwards in magazines such as 'The All-Story', 'The Cavalier' and 'The Argosy', as well as in novel form.  She also used the pen names David Fox and Douglas Grant. One of her notable contributions to the mystery genre was the introduction of blind detectives, and it’s possible that she was the first writer to do this. Her character Damon Gaunt, whose blindness was compensated by extraordinary powers, first appeared in the 1915 novel 'At One-Thirty', though earlier short stories featuring Gaunt may have been published in now-lost periodicals.

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By the 1920s, Ostrander had achieved such prominence that Agatha Christie parodied her style in 'Partners in Crime', where her sleuthing duo Tommy and Tuppence emulate Ostrander’s detectives McCarty and Riordan.

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Ostrander died of heart disease in Long Beach, New York, on 26 April 1924.