Morton Dill

Morton Dill was an American tourist from Alabama who visited New York City in 1966. While on the Empire State Building's observation deck, he encountered the First Doctor, his companions Ian Chesterton, Barbara Wright and Vicki Pallister and a Dalek. He assumed they were all actors. (TV: The Chase, ep. "Flight Through Eternity")

Behind the scenes
Morton Dill was played by Peter Purves, who began his tenure as companion Steven Taylor in the sixth episode of The Chase, "The Planet of Decision."