Hollywood star Johnny Depp accused his former wife Amber Heard of lying about him beating her, and told London's High Court on Tuesday that she had struck him.
Depp, 57, star of the Pirates of the Caribbean films, 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 he had beaten actress Heard, causing her to fear for her life.
They said this occurred during violent rages brought on by alcohol or drugs, and sometimes after he falsely accused her of infidelity.
"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.
He depicted his former wife as a calculating, emotionally dishonest narcissist.
Wearing a dark suit and glasses, Depp gave evidence at the start of the case at London's High Court.
Heard, who arrived wearing a red scarf tied around her face, is also due to give evidence.
In a written statement outlining Depp's case, his lawyer David Sherborne said Heard had first spoken about the abuse claims in May 2016.
Mr Sherborne said 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," he 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 said Heard had begun an affair with Tesla chief executive Elon Musk in early 2015 shortly after she married the actor.
They said she had 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 former wife and had 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."
The couple met on the set of the 2011 film The Rum Diary and married in February 2015.
Heard filed for divorce after 15 months, and days later obtained a restraining order against Depp.
Their divorce was finalised in 2017, when the restraining order was dismissed.
Cross-examined by lawyer Sasha Wass, Depp agreed he had taken "every drug known to man" by the age of 14.
He said he 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," Depp said.
The court was shown mobile phone footage taken by Heard which showed an angry Depp slamming kitchen cupboard doors and pouring himself a "mega" glass of wine.
"I can only say I was upset, very upset," he said. He said it was not a pleasant video to watch.
Ms Wass said he would turn into an alternate personality that he described as "the monster", which was brought on by anger, jealousy or drugs.
He said "the monster" Heard referred to was when he yelled back at her in arguments.
"It would become a screaming match and that was the monster," Depp said. "It's not Dr Jekyll and Mr Hyde."
He denied Wass's suggestion that he had a "nasty, angry side".
The actor is also being sued by a crew member from one of his films in 2018, who accused him of punching him twice in the ribs, the court heard.
Ms Wass recounted a statement from actress 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. "I do not have an anger-management problem."
In his witness statement, he said Heard had thrown a vodka bottle at him, severing his finger.
The case is set to last for three weeks, Judge Andrew Nicol said.
Also due to give evidence by videolink are Vanessa Paradis, Depp's former partner, and actress Winona Ryder.