Suddenly he was hit in the face, either slapped or punched, police aren't sure.
But they say a Ukrainian reporter named Vitalii Sediuk jumped the rope and grabbed for Pitt.
Video captures the moment-- Pitt's bodyguards pounced-- and Sediuk is hauled away in handcuffs..
It all happened at the premiere of Angelina Jolie's movie, "Maleficent".
Unfazed, the couple continued to walk the red carpet.
How this guy was able to get so close to a Hollywood star and why he attacked Pitt is anyone's guess, especially since he's been in hot water for stunts like this one before.
Two years ago- May 2012- at the premiere of Men in Black 3 in Moscow, he made headlines after kissing actor Will Smith, who didn't take too kindly to the PDA.
Smith told reporters Sediuk was lucky he didn't "sucker punch him."
Perhaps his biggest prank took place at last year's Grammy awards.
Not only did he elude security to get a second-row seat but despite having no credentials, he jumped on stage.
He tried to grab the Grammy award from Jennifer Lopez to present it to the singer Adele.
He was arrested offstage, but only after telling Adele he loved her .
After that, he accepted a plea deal for probation- agreeing to stay out of trouble for three years.
That didn't last.
After being denied credentials at the Oscars-- just weeks later in March last year- Vitale Sediuk showed up on the red carpet wearing this!
He called it a protest after being blacklisted by awards show producers.
Police ordered him to leave.
Just this year- in Los Angeles- he grabbed a hold of actor Bradley Cooper's leg- holding on for dear life.
Security had to peel him off.
The next month - he got a little too close for comfort for actor Leonardo Dicaprio at a Santa Barbara film festival.
Earlier this month-- he was at it again- trying to crawl under actress America Ferrera's dress at a Cannes Film Festival red carpet event.
He was dragged away, and later fired from his reporting job with a Ukrainian television station.
After this latest prank on Brad Pitt, Vitale Sediuk is facing a misdemeanor charge and perhaps months in jail.
The actor has been granted an emergency protective order against him.
(Randi Kaye for CNN's Hollywood Minute)
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