Mummer (Margaery Tyrell)

An actress playing Margaery Tyrell is a cast member of The Bloody Hand, a comedic theatre troupe in Braavos. She is played by Eva Butterly.

Season 6
The mummer plays Margaery Tyrell in a production of The Bloody Hand. She is seen by Arya Stark backstage.

In the books
In the novels, there is no such character. The play "The Bloody Hand" does not include Margaery's character.