Johnny Depp visits children's hospitals unannounced in his Captain Jack Sparrow costume.

He told an audience at the 'Produced By' Conference: "He knows he is a very fortunate person and he wants to give back."

The 50-year-old star has played Captain Jack Sparrow - a mischievous but loveable pirate - in four blockbuster films and the character strikes a particular chord with Johnny's younger fans.

In 2010, the actor accepted an invitation from nine-year-old girl Beatrice Delap to appear at her school in London after she discovered he was filming 'Pirates of the Caribbean: On Stranger Tides' film at the nearby Old Royal Naval College.

The schoolgirl wrote a letter to Johnny asking him to visit Meridian Primary School in Greenwich, and the star obliged, surprising excited pupils in full Captain Jack garb at a school assembly.

Beatrice said at the time: "It was the most exciting school day ever. I had the idea to write the letter last week after me and a friend went to see the film set. Pat from the school office delivered it. Yesterday the school called us in for a special assembly at the end of the day. They told us there had been a couple of incidents in the playground.

"Then Johnny Depp walked in dressed as Captain Jack. There were gasps and screams. He pulled the letter out of his pocket and said he was going to frame it. Then he called me down and gave me a hug."