Taylor Swift, Jim Parsons, Lady Gaga: A day out in Hollywood

Here's what your favourite Hollywood stars have been up to.

Singer Taylor Swift poses with musician Jon Bon Jovi during the Centrepoint Gala Dinner at Kensington Palace in London on November 26.

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US President Barack Obama bumps elbows as a greeting with actor Steve Martin, as fellow actor Jim Parsons looks on during Obama's tour of Dream Works Animation in Glendale, California, November 26.

Martin said he preferred to bump elbows rather than shake hands as he had a cold.

Martin and Parsons are the voices in the upcoming animated movie Home.

Singers Niall Horan (left) and Harry Styles laugh as they perform as One Direction on ABC's Good Morning America program inside of Central Park in New York.

Singer Lady Gaga gets ready to meet her fans -- who she's lovingly christened Little Monsters -- at Narita international airport in Narita, east of Tokyo in Japan.

Cast member Bryan Cranston signs a barrel shaped box containing the Blu-Ray set of the final season of the television series Breaking Bad at Barnes & Noble at The Grove in Los Angeles, California.