As 'People' magazine reports, Cox didn't mince words when talking about Phoenix's performance.

The 77-year-old 'Succession' star called Joaquin Phoenix's performance as Napoleon Bonaparte in Ridley Scott's biopic 'Napoleon' "awesome" during a conversation at the British Library in London.

"It's really appalling," the Scottish actor said of "a truly terrifying performance by Joaquin Phoenix", reports The Standard.

"I don't know what he was thinking."

According to People, Phoenix, 49, played Napoleon Bonaparte in the Oscar-nominated historical drama directed by Scott and written by David Scarpa, which was released last November.

The 'Joker' Oscar winner stars alongside Vanessa Kirby as Josephine de Beauharnais, Tahar Rahim as Paul Barras, Rupert Everett as Arthur Wellesley, and Ben Miles as Armand de Caulaincourt.

In his conversation with moderator Clive Myrie titled 'History on Stage n Screen', Cox said of the lead role of Napoleon, "I would have played it a lot better than Joaquin Phoenix, I tell you that."

He said the blame was on Phoenix, saying, "I don't think Ridley Scott helps him as a director of the movie".

Cox said: "I think he's got a good name. Joaquin... weird-weird... weird. It's kind of a weird performance."

Regarding the historical accuracy of 'Napoleon' and other epics like it, Cox reportedly said: "You can say it's a good play. No – it's a lie."

He called the 1995 Best Picture Oscar winner Braveheart "a load of crap", adding that director-star Mel Gibson was "wonderful, but it's a pack of lies".