Best known as Nurse Chapel and the voice of the computer on Star Trek, Barrett-Roddenberry had been suffering from leukemia which had been diagnosed earlier this year.
She also played Lwaxana Troi on Star Trek The Next Generation.
She had just completed voice recording for Star Trek XI, meaning she had featured in almost every movie and series of the long-running franchise.
She also had recurring roles on Babylon 5 and Earth: Final Conflict.
A firm fan favourite, she will be sorely missed, and our condolences are with the family.