Margot Robbie has been called out for dismissing Halloween costume guidelines issued by the Screen Actors Guild-American Federation of Radio and Television Artists (SAG-AFTRA).

Last week, the performers union advised its members to 'choose costumes inspired by generalised characters and not to 'post photos of costumes inspired by struck content to social media.'

But Margot ignored protocol and dressed up as vigilante V from the cult film V For Vendetta as she attended the Casamigos Halloween party in Los Angeles on Friday.

Fans have now called the Australian actress for dismissing costume guidelines, with one writing: 'She's treading a thin line with the costume…'

'I thought actors weren't allowed to dress up as characters? Look at who she's dressing up as. Could it be symbolic or do you think with everything going on they CARE about some stupid rules even if it might impact their bookings???' another said.

'If Megan Fox is getting criticised, what's different here? No matter what anyone says, the first impression here is recognisably V For Vendetta,' a third wrote.

The Australian actress went completely incognito in the costume as she arrived to the star-studded bash.

Margot wore an all-black ensemble consisting of a tight pencil dress, duster coat and heeled boots, while completing her look with V's famous bob wig.