"Pirates of the Caribbean" star Johnny Depp denied ever physically abusing Amber Heard as he took the witness stand on Tuesday at the US defamation trial against his former wife.

"There were arguments and things of that nature but never did I myself reach the point of striking Miss Heard in any way," Depp told the jury hearing the case at the Fairfax County Circuit Court in Virginia.

"Nor have I ever struck any woman in my life," he said.

Depp said the "heinous and disturbing" allegations of domestic abuse made against him by Heard were "not based in any species of truth" and came as a "complete shock."

Depp was asked by one of his lawyers why he had brought the defamation case against his ex-wife.

"I felt it my responsibility to stand up not only for myself, but stand up for my children," Depp said. "I wanted to clear my children of this horrid thing that they were having to read about their father that was untrue."

"It's strange when one day you're Cinderella, so to speak, and then in 0.6 seconds you're Quasimodo," he added.

The 58-year-old Depp, his hair slicked back in a ponytail and wearing a black suit, black shirt and floral pattern tie, took the stand on the fifth day of the blockbuster defamation trial.

Depp filed the defamation suit after Heard, who turns 36 on Friday, wrote a column for The Washington Post in December 2018 in which she described herself as a "public figure representing domestic abuse."

The actress never named Depp, whom she met in 2009 on the set of the film "The Rum Diary," but he sued her for implying he was a domestic abuser and is seeking $50 million in damages.

Heard, who was married to Depp from 2015 to 2017, countersued, asking for $100 million and claiming she suffered "rampant physical violence and abuse" at his hands.

Depp accuses Heard of seeking to "generate positive publicity for herself" ahead of the release of the film "Aquaman," in which she had a starring role.

Depp filed the defamation complaint against Heard in the United States after losing a separate libel case in London in November 2020 that he brought against the tabloid The Sun for calling him a "wife-beater."

- 'Never seen Johnny abuse anybody' -

In opening arguments, Heard's lawyers alleged that Depp became a "monster" during drug- and alcohol-fueled benders and physically and sexually abused Heard.

Depp's attorneys rejected the allegations as untrue and said they have had a "devastating" impact on the actor's Hollywood career.

He left his role as Captain Jack Sparrow in the "Pirates of the Caribbean" franchise and was asked to step down from the "Fantastic Beasts" series based on the book by Harry Potter author J.K. Rowling.

Depp took the witness stand following testimony from a member of his security detail, Sean Bett, and Keenan Wyatt, who worked as a sound engineer on many of his movies.

Both men testified that they had never seen Depp be violent in any way.

"I've never seen Johnny abuse anybody ever," Wyatt said.

Bett said he had witnessed Heard though once throw a "water bottle or a plastic cup" at Depp.

Depp filed his case in Virginia since the Post is printed there but he is not suing the newspaper itself.

Virginia also has defamation laws considered to be more favorable to plaintiffs than those in California, where the two actors live.

In 2016, Heard sought a restraining order against Depp amid abuse allegations. Their divorce was finalized in 2017.