The 57-year-old Pirates of the Caribbean star is suing The Sun’s publisher News Group Newspapers and its executive editor Dan Wootton for libel over an article Wootton wrote in April 2018 calling him a “wife beater”.

The paper’s lawyers said they would show the claim was true and that Depp had beaten Heard, causing her to fear for her life, during violent rages brought on by alcohol or drugs, sometimes when he had falsely accused her of infidelity.

The actor became an alternate persona which he himself described as “the monster”, they said.

“For the avoidance of any doubt, I have never abused Ms Heard, or, indeed, any other woman, in my life,” Depp said in a witness statement in which he characterised his ex-wife as a calculating, sociopathic, emotionally dishonest narcissist.

Wearing a dark suit and glasses and speaking in a deep clear tone, Depp gave evidence at the beginning of the case at London’s High Court on Tuesday.

In a written statement outlining Depp’s case, his lawyer David Sherborne said Heard had first aired the abuse allegations in May 2016, saying it was hard to think of “more extreme or violent” claims of abuse than she would make during the trial.

“The Claimant’s position is clear; Ms Heard’s allegations are complete lies,” Sherborne said.

“The Claimant was not violent towards Ms Heard, it was she who was violent to him.”

In papers submitted to the court, Depp’s team also said Heard had begun an affair with Tesla chief executive Elon Musk in early 2015, shortly after she married Depp.

Heard also allegedly engaged in at least one extra-marital relationship with her co-stars, with actor James Franco named.

Appearing in the witness box, Depp said he was the victim of attacks from his ex-wife and had himself sought to avoid confrontation.

“I would try to go to my own corner as it were,” he said.

Asked about one argument, Depp said “it escalated and it got physical … Miss Heard struck me”.

Cross-examined by lawyer Sasha Wass, Depp agreed he had taken “every drug known to man” by the age of 14 and said he had had a difficult childhood and struggled to come to terms with his fame and success.

“Even when I speak my own name it sounds foreign to me,” he said.

He denied Wass’s suggestion he had a “nasty, angry side” as she told the court he had trashed a New York hotel room and threatened paparazzi in London, when he said he had hit one photographer’s hand with a piece of wood.

Wass also recounted a statement from actor Ellen Barkin, who said Depp had thrown a bottle of wine across a hotel room on one occasion and had become jealous and angry.

“Untrue,” Depp replied, saying Barkin held a grudge.

-AAP