'Harry Potter' audiobook narrator Stephen Fry said AI was used to steal his voice, and warned that convincing deepfake videos of celebrities will be next

• Actor Stephen Fry issued a warning about AI cloning his voice at the CogX Festival on Thursday.
• Fry said his readings of the "Harry Potter" audiobooks were input into an AI and used to create new audio.

Actor Stephen Fry sounded the alarm on AI at the CogX Festival on Thursday saying the technology had been used to clone his voice to create audio illegally, according to various reports including from Fortune and Deadline.

Fry played a clip at the festival of an AI system that copied his voice to narrate a historical documentary and pointed out that AI is a "burning issue" for the actor's union SAG-AFTRA, of which he is a member.

"I said not one word of that — it was a machine. Yes, it shocked me," he told the audience about the audio.

"They used my reading of the seven volumes of the Harry Potter books, and from that dataset, an AI of my voice was created, and it made that new narration."

He explained that the audio resulted from a "mashup," created from a "flexible artificial voice, where the words are modulated to fit the meaning of each sentence."

He added: "It could therefore have me read anything from a call to storm Parliament to hard porn, all without my knowledge and without my permission. And this, what you just heard, was done without my knowledge. So I heard about this, I sent it to my agents on both sides of the Atlantic, and they went ballistic — they had no idea such a thing was possible."

Fry said he warned his agent that this was just the beginning.

"It won't be long until full deepfake videos are just as convincing," he said.

Hollywood actors and writers have been striking for months to express their anger at a number of issues in the industry, including royalties from streaming platforms.

Another top issue during the strike is how studios plan to use AI. Members of the SAG-AFTRA union say the studios they're negotiating with proposed to pay background actors for an AI day where a scan is taken of them to create a digital likeness and used in future content without compensation or consent.

"Actors now face an existential threat to their livelihoods with the rise of generative AI technology," Duncan Crabtree Ireland, the union's national executive director and chief negotiator said.

Henry Ajder, an AI expert and presenter, who is on the European advisory council for Meta's Reality Labs, previously told Insider that AI could be used in the future to create nonconsensual deepfake pornographic images and videos of actors.

For example, a deepfake app called FaceMega promoted a sexually suggestive advert in March, by using actress Emma Watson's face superimposed onto the body of another woman.