Grace Lee Whitney, who played Captain Kirk's assistant on the original Star Trek series, has died. She was 85.

Whitney died of natural causes Friday in her home in the central California town of Coarsegold, about 80 kilometres north of Fresno, her son Jonathan Dweck said on Sunday.

Whitney played Yeoman Janice Rand in the first eight episodes before being written out of the series. In her 1998 autobiography The Longest Trek: My Tour of the Galaxy, she wrote that her acting career largely came to an end and she became an alcoholic.

Grace Lee Whitney Star Trek

Star Trek cast member Grace Lee Whitney attends the VIP Open House at the Light Speed Fine Arts gallery December 08, 2001 in Laguna Hills, Calif. (Sebastian Artz/Getty Images)

She wrote that she struggled with her addiction for many years before getting treatment and regaining her career with the help of Leonard Nimoy, who starred as Spock in the series.

She returned for the movie franchise, reprising her role in Star Trek: The Motion PictureStar Trek III: The Search for SpockStar Trek IV: The Voyage Home and Star Trek VI: The Undiscovered Country.

Dweck said his mother would have liked to be remembered more as a successful survivor of addiction than for her Star Trek fame. She dedicated the last 35 years of her life helping people with addiction problems, some of whom she met at Star Trek conventions, he said.

"Over time, she became appreciative of her short time on Star Trek because she developed meaningful relationships with the fans, Leonard Nimoy and other cast members," Dweck said.

Besides Jonathan, she was survived by her other son, Scott Dweck.