As Captain Kirk in Star Trek, William Shatner took us to places “where no man has gone before”, with stories that foreshadowed the invention of the mobile phone and tablet computers. Now, in real life, the actor is exploring virtual reality — but he wants the entertainment industry to be aware of its potential detrimental impact on vulnerable minds.

Shatner told the Guardian: “The use of technology to affect our minds is so powerful now that we need to be on guard in the future.”

He is involved with Ziva Dynamics, a VR company, through which he has experienced “nightmarish footage” involving strange creatures that creep up on the user.

“It’s so real: it’s the stuff of nightmares... We’ve got to be really careful because you could put somebody into a psychosis,” he said.

Shatner also spoke of experiences created by the Jet Propulsion Laboratory, a research centre that works for Nasa. It had turned space footage into 3D, he said, describing how, with VR goggles, he “walked on Mars”.

“I felt the stones under my feet and went down a hill. I felt my feet were moving more quickly down the hill. Then this creature crept up on me. It was a screaming nightmare,” Shatner said.

“We’ve got to be very careful we don’t do terrible things to people on the verge, whose view of reality is somewhat misty.”

But he also sees the beneficial potential of VR for medical uses, such as helping children with autism experience emotions. It could also help grieving families, he said: “One of the things that I suggested... was the possibility of people, prior to dying, [making] a little speech to a virtual-reality camera. Then you could put that by their grave and people who loved them, or were curious about them, could see them in their entirety, in absolute reality... There they are, saying, ‘my darling, I love you’.”

Shatner, 87, is about to publish a memoir. In one passage, he writes of having his body reproduced in VR — “everything necessary to enable technicians to make my image move and speak realistically”.

“Because of that image,” he jokes, “Shatner will now ‘live’ forever.”

The Hollywood Walk of Fame describes Shatner as “a cultural icon”. As the captain of the USS Enterprise, he starred in the Star Trek television series between 1966 and 1969. It was cancelled after just three seasons, but went on to become a cult hit, inspiring a franchise of films.

He learned his craft as a classical Shakespearean actor and was cast in his first major film role in 1958, when he played opposite Yul Brynner in an adaptation of Fyodor Dostoyevsky’s The Brothers Karamazov. His subsequent performances won him Golden Globe and Emmy awards.

Asked about the way that the original Star Trek series predicted future technology, he said: “Science fiction can portend the future. It has in many places. Going to the moon was devised by science fiction writers.”

But stories were the main strength of the original Star Trek series, he added: “Great stories. One guy who was half black and half white — black on the left side, and white on the right side. He hates the guy he meets who’s black on the right side and white on the left side. The idiocy of racism is shown just by that example. It’s perfect.

“Also, computer wars where nobody dies. Countries wrecked by computer wars are around the corner. Science fiction is a glimpse into the future with somebody else’s imagination.”

Shatner’s book Live Long and... What I Learned Along the Way will be published next month.