US actress Angelina Jolie is seen upon arrival for the world premiere of her husband Brad Pitt's film "World War Z" in London June 2, 2013, and the Spanish premiere of the movie "The Tourist" in Madrid December 16, 2010, in this combination picture made June 2, 2013. Sunday marks Jolie's first public appearance after announcing she underwent a double mastectomy in February 2013.[Photo/Agencies]

Photos: 'World War Z' premieres in London

In "World War Z", Pitt plays United Nations representative Gerry Lane who is enlisted to help stop a zombie pandemic that is toppling armies and governments and threatening to destroy mankind.

Pitt said he was proud of the film and also of Jolie for her decision to have a mastectomy for the sake of their family and to share that experience.

"When she's faced with a problem - and we have known this was coming for some time - she takes it by the horns," Pitt, 49, also dressed in black, told reporters. "I'm super proud of her. She's a bad ass."

Asked how important it was to have her on the red carpet with him, Pitt said: "It's just more fun to do these things with each other. More fun when she's around and same for her."

"World War Z" marks Pitt's first foray as the star and producer of his own potential franchise.

Pitt said his own children's reaction to the book sparked the project which ultimately was about survival and family.

"The boys love a zombie," he said.