Hanks, 64, appeared via video link in a new episode of The Graham Norton Show, strategically covering up his head with a baseball cap until he was ready for the big reveal.
Speaking remotely from Australia, Hanks said: "I am working on Baz Lurhmann's movie about Elvis Presley - Austin Butler is playing Elvis Presley.
"And here, let me show you the horrible haircut I have to have in order to portray Colonel Tom Parker."
He then pulled off his hat, but teasingly stood up so that the top of his head was out of view, saying: "Check out this horrible ... Can you see that? Look at that thing!"
Eventually Hanks bent down so that his whole head came into frame, giving us a brief glimpse of his shiny hairless head.
As the audience groaned in shock, Hanks joked: "I just scared the children.
"I want to apologize for showing that."
Hanks also made a quip about playing Graham Norton on screen, which was a concept the show's host embraced.
"What I really want to do is just have a little tuft of hair right here and then a big, big beard, and then everybody would think I'm Graham Norton," Hanks said.
As everyone laughed, Norton said it would be 'uncanny', adding: "You can play me in the biopic."
Hanks replied: "Evidently, that's my gig now, so I only play real people in show business."
Hanks is featuring in next year's Elvis, the forthcoming biographical film about rock-and-roll legend Elvis Presley.
Directed by Baz Luhrmann, it will chronicle the life and career of the singer, who is being played by Austin Butler.
It is due to be released on 5 November 2021, having resumed shooting in September after a six-month shutdown in production.
Luhrmann said in a statement at the time: "We're back to, as Elvis liked to say, 'taking care of business!'
"It is a real privilege in this unprecedented global moment that Tom Hanks has been able to return to Australia to join Austin Butler and all of our extraordinary cast and crew to commence production on 'Elvis."
He continued: "I cannot emphasize enough how lucky we feel in the current climate that the state of Queensland, and Queenslanders in general, have been so supportive of this film.
"We thank our partners in the Queensland Government and Queensland Health for their extremely diligent process, so that we can be an example how creativity and productivity can proceed safely and responsibly in a way that protects our team and the community at large."
Featured Image Credit: BBC