Harry Trant was a space traveller.
Biography
Harry was travelling in his spaceship when it was swallowed by a living planet. After escaping the planet, Harry spent around a week on its bare surface. He met the Third Doctor, whose craft had also been swallowed by the planet. They made their way into the planet's stomach, where the Doctor used his TARDIS to escape the planet. The Doctor took Harry back to his home planet in the TARDIS. (TVA: The Hungry Planet)