Hollywood star Johnny Depp on Friday accused British tabloid newspaper The Sun of turning him from "Cinderella to Quasimodo" by claiming he beat his ex-wife Amber Heard.

The "Pirates of the Caribbean" star also told a London court that he knew his marriage to the 34-year-old actress was over when the cleaner discovered human faeces in the couple's bed.

"I thought it was an oddly fitting end to the relationship," the 57-year-old said.

The first week of the star-studded libel trial against The Sun's publisher and executive editor ended with Depp denying hurling a magnum of champagne and a phone at Heard while he was high.

Depp claims charges compiled by Heard during a tumultuous two-year marriage that ended in 2017 were a "hoax" designed to advance her career at his expense.

The High Court trial revolves around a 2018 headline in The Sun asking how "Harry Potter" author JK Rowling could support casting "wife-beater" Depp in a "Fantastic Beasts" film.

Johnny Depp said the headline in The Sun tabloid altered his Hollywood image and endangered his career
Johnny Depp said the headline in The Sun tabloid altered his Hollywood image and endangered his career AFP / DANIEL LEAL-OLIVAS

Depp said the headline altered his Hollywood image and endangered his career.

"I went from Cinderella to Quasimodo in 0.6 seconds," he said. "I was without a voice."

Depp looked more confident and engaged on the fourth day of the three-week hearing than he did at its start.

News Group Newspapers' lawyer Sasha Wass tried to complete her depiction of the superstar as self-centred and out of touch with reality due to debilitating drug abuse.

Depp countered that it was Heard who was always looking for a fight.

Depp's defence is trying to portray Amber Heard, pictured Thursday at the High Court, as a manipulative and scheming publicity seeker
Depp's defence is trying to portray Amber Heard, pictured Thursday at the High Court, as a manipulative and scheming publicity seeker AFP / JUSTIN TALLIS

He said he went to read in bed on the night of Heard's 30th birthday party because he was "trying to avoid another confrontation" with her.

But Wass said Depp was fuming after Heard had pointed out he was two hours late.

"And you picked up the bottle of champagne and you threw it at Ms Heard. And it missed and the bottle hit the wall and it smashed," the lawyer said.

"And that, I suggest, is how you express yourself when you are angry, you smash things," the lawyer said.

Depp denied this happened and countered: "I disagree."

Depp has said he was often high or strung out on drugs and "in no condition" to hurt Heard
Depp has said he was often high or strung out on drugs and "in no condition" to hurt Heard AFP / Ben STANSALL

The couple's marriage was ending by the time Heard accused Depp of hitting her in the face with a phone in May 2016.

Wass said Depp "wound up like a baseball pitcher" and threw the phone at his wife while one of her friends was on the other line.

Depp denied this but admitted that Heard asked the friend to call the police.

He also said the security on site witnessed how the entire episode was staged.

"She was screaming, 'stop hitting me, Johnny! stop hitting me, Johnny!' and the security came and she was still screaming... and I was 20 feet away getting something from the fridge," Depp said.

"And then (one of the guards) said 'boss, let's get out of here'."

Wass submitted a photo that she said showed a red bruise on Heard's cheek from the impact of Depp's phone.

But a Los Angeles policewoman who was called to the scene testified that she did not detect any bruising.

"Her face was red. It was clear that she was crying," officer Melissa Saenz told the court by video link.

Lawyers for both sides have spent much of the court time reading past texts and emails filled with obscenities and graphic content more typical of Hollywood movies than the hushed vaulted surroundings of the Royal Courts of Justice.

Depp's defence on Thursday rested on a claim that he was so often high or strung out that he was in no physical condition to hurt Heard.

He spent a part of Friday arguing with Wass about whether the faeces found in the couple's bed were human.

Depp said it was not "physically possible" for one of their dogs to have left it there because it was simply too big.

"I was convinced that it was either Ms Heard herself or one of her cohort involved in leaving human faeces on the bed," he said.

He called the entire episode "a mystery".

Depp's lawyer then read an alleged party invitation from Heard that said: "Bring some food, booze and drug of choice!"

Another text Heard allegedly sent from Depp's phones asked a friend to "procure more mushrooms".