As the sultry communications officer Lt. Uhura on the original "Star Trek," Nichelle Nichols made waves on primetime televison like no African-American actress did. Unfortunately, her last years were spent suffering in secret, as she refused to let people see she was undergoing some terrible ordeal. Ultimately, after suffering a series of health difficulties, she passed away on Sunday at the age of 89.

It is only when she died that what she bravely went through were brought to light by those very close to her and whom she entrusted with the truth.

In June 2015, the actress who shattered racial barriers in the 1960s was confined to a wheelchair after a stroke left her right side immobile.

In addition, Radar Online has learned that the actress has been diagnosed with moderately progressing dementia. The tragic actress appeared weak and exhausted in several of her final public appearances, yet she was still able to attend Star Trek fan conventions.

"For years, many around her thought she was on her last legs," a family insider shared to the online entertainment site. "It was terrible to see her this way because she was once so vital."

In 1966, Nichols joined William Shatner and Leonard Nimoy in the primary cast of NBC's Star Trek. As Nyota Uhura, she assisted Captain Kirk and the Enterprise crew in making contact with extraterrestrial lifeforms.

Nimoy's passing in 2015 and that of James Doohan, who portrayed engineer Montgomery "Scotty" Scott, left Nichelle, William Shatner, and George Takei as the only original Star Trek cast members still alive.

A friend who was with her in the final years of her life added: "Nichelle never feared death. She believed she'd be reunited with her beloved brother Thomas."

Kyle Johnson, Nichols' 70-year-old son, verified the devastating news of her passing on her official Facebook page on Sunday morning.

"I regret to inform you that a great light in the firmament no longer shines for us as it has for so many years," Johnson wrote on Sunday, July 31. "Last night, my mother, Nichelle Nichols, succumbed to natural causes and passed away," he wrote. "Her light however, like the ancient galaxies now being seen for the first time, will remain for us and future generations to enjoy, learn from, and draw inspiration," he continued. "Hers was a life well lived and as such a model for us all," he added.

Since 2018, Nichols has been under conservatorship. After her former manager Gilbert Bell was accused of financially exploiting Nichols, her son Kyle Johnson successfully petitioned to be her conservator. Protesters believe Nichols is of sound mind and desires to be liberated from the contract.