A death certificate has revealed Betty White's cause of the death. 

The document was obtained by TMZ, and the Golden Girls star's cause of death was listed as a "cerebrovascular accident" – the medical term for a stroke. 

Sources who spoke to the outlet says she had been "alert and content" after the stroke and prior to her death. 

The legendary actress died aged 99 just weeks before what would have been her 100th birthday. 

White's agent Jeff Witjas has previously shared with the public that she died of natural causes. 

"Betty died peacefully in her sleep at her home," he told People in a statement. 

Witjas also quashed unfounded claims White's death was related to her booster shot she received days earlier. 

"People are saying her death was related to getting a booster shot three days earlier but that is not true," Witjas said. 

He added: "Her death should not be politicised – that is not the life she lived." 

Witjas confessed he thought the star "would live forever". 

Her last words before she died was her husband's name, Allen Ludden, Page Six reports. 

"I will miss her terribly and so will the animal world that she loved so much. I don't think Betty ever feared passing because she always wanted to be with her most beloved husband, Allen Ludden. She believed she would be with him again." 

A documentary about the star will debut on what would have been the star's 100th birthday. 

The Golden Girls legend had collaborated with producer Steve Boettcher - who had been working on the pending special Betty White: A Celebration to mark what would have been her 100th birthday on January 17 - and she filmed a message for her fans on December 20, just a week and a half before her death on New Year's Eve. 

He told Entertainment Tonight: "On December 20, she did a short little video for us... it was kind of a tribute to her fans that were going to be with her at the event. It's kind of a shout-out to her fans that she did 10 days before she passed away." 

Boettcher added: "You'll see that in the movie coming out on the 17th of January, that she has this unbelievable look at life and view of life and that it just rains through her entire career and her personal life. [She was] just the eternal optimist."