The heir to the British throne, 44, has in recent years regularly appeared in less formal settings in a bid to connect with younger audiences, including Radio One, one of UK's biggest stations for under 30s, and sports podcasts.
William surprised celebrity guests including actors Cate Blanchett and Hannah Waddingham when he joined them on the sofa for an episode of the BBC's Graham Norton Show, which is due to air later on Friday.
Asked about how he relaxes, he said he and his family together enjoy reality show The Celebrity Traitors, while he personally turns to music and films.
"I'm a big fan of everything Christopher Nolan does. His films are fantastic – The Dark Knight series is psychologically dark and deep and I absolutely love that," William said.
"He takes concepts that are completely out there and makes them incredibly entertaining."
Before accepting that his future job would be that of King, he said he had wanted to be a policeman.
"Then I went through a phase of wanting to be a DJ - I wasn't very good," he said.
William has in recent years sought to provide insights into his personal life, without creating waves by giving too much away about the challenges of life in the public eye.
Talking about The Earthshot Prize, which he set up six years ago to award five winners STG1 million ($A1.9 million) each to fund their ideas to save the environment, William said the aim was to bring optimism into a issue which can otherwise feel depressing.
"There are some amazing people out there doing things to protect the world," he said.
with PA
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