Black was carried onto the red carpet in a litter
Film star Jack Black demonstrated his martial arts moves and hugged and high-fived fans at the London premiere of hit comedy Kung Fu Panda.
Co-stars Lucy Liu and Dustin Hoffman demonstrated the more peaceful art of origami in front of reporters.
The animated film follows the story of bungling panda Po - voiced by Black - who aspires to be a kung fu warrior.
Angelina Jolie and Jackie Chan, who also voice characters in the film, did not attend the screening.
The film had its world premiere at the Cannes Film Festival in May and opens in UK cinemas next month.
Fans in London's Leicester Square were entertained by dragon dancing, contortionists and kung fu demonstrations.
After showing off his moves on the red carpet, Black admitted: "I'm not a violent person by nature.
Black demonstrated kung fu moves at the premiere
"If I see violence happening on an unsuspecting victim, my tendency is to rescue.
"The only time I'm really going to bust out the moves is for self-defence."
During an interview to promote the film in Cannes, Black accidentally confirmed the open secret that Jolie was pregnant with twins.
But he told reporters on Thursday night: "I don't want to spill any beans because I got in trouble last time I spilt the beans.
"I'm keeping all my beans to myself this time."
Charlie's Angels star Liu made a boat out of paper while Hoffman, who voices the red panda, Shifu, made a paper plane before throwing it into the crowd.
He's a tremendous person - I just went in and had a blast
Liu, wearing a red dress, said she was a "huge fan" of Black.
The actress, who voices Viper, said: "He's a tremendous person - I just went in and had a blast. He's so much fun."
The film has been a hit in the US and Canada, taking $60m (£30.4m) on its opening weekend at the box office.
But some Chinese people are urging the country's censors to ban the film there in revenge for Steven Spielberg's decision to pull out of the Olympics in his role as artistic adviser.
Spielberg founded Dreamworks, the production company behind Kung Fu Panda.