Martel grew up in modest circumstances in the Bronx, New York, before the employer of her mother sent her to his own cost, a boarding school in Connecticut. Later she attended the prestigious High School of the Performing Arts in her hometown, where she graduated with honors. Subsequently, she appeared on Broadway in New York and graduated from the end of the 1950s television appearances regularly. Her debut on the big screen was in 1964 with Antonio Martel Santeans Mystery film The Glass Cage, before a broad American audience for her role as T'Pring in the Star Trek episode Amok Time and The Outer Limits episode Demon with a Glass hand was known.
The 1.68 m tall actress was married to four years younger American fellow actor Jerry Douglas. From the divorced marriage two children were born. She now lives in Santa Monica, California.