The “Aquaman” star wrote that Depp regularly made the threat, especially later in their relationship. She added that he also subjected her to "punching, slapping, kicking, head-butting and choking," during their time together.
Heard's testimony was released as she took to the witness box in the British capital's Royal Courts of Justice, where she began three days of evidence as part of Depp's libel case against The Sun newspaper over a 2018 article that labelled him a "wife beater.”
Depp, 57, is suing the tabloid’s publisher, News Group Newspapers and the newspaper's executive editor, Dan Wootton, over the article, headlined: "Gone Potty: How can JK Rowling be 'genuinely happy' casting wife beater Johnny Depp in the new Fantastic Beasts film?"
Heard, 34, alleged that “some incidents were so severe that I was afraid he was going to kill me, either intentionally or just by losing control and going too far.”
The “Pirates Of The Caribbean” star was "very good at manipulating people" and would blame his actions on a "self-created third party" he called the "monster,” her statement said.
"He would speak about it as if it was another person or personality and not him doing all these things,” it added.
Heard also described an incident in January 2015 in a hotel room in Tokyo over a prenuptial agreement and suggested they had argued about it.
She alleged that it "resulted in Johnny kneeling on my back and hitting me on the back of the head.”
Heard, who has been present throughout the trial, will be questioned over 14 allegations of domestic violence which The Sun’s publisher is relying on to defend the April 2018 article.
Over nine days of evidence so far, testimony about Depp’s lifestyle, use of drink and drugs and attitudes towards women has been heard in the court.
Depp claims Heard was the aggressor during their relationship, which he likened to "a crime scene waiting to happen." Several current or former employees have backed his version of events.
But Heard claimed in her testimony that Depp "often didn't remember what he had done" because of the amount of alcohol and drugs he had consumed, and that "it was as if it hadn't happened for him."
The case is expected to conclude next week.
This article was originally published on NBCNews.com.