What is the name of the Doctor's granddaughter in the early episodes?

The Doctor’s granddaughter in the early Doctor Who episodes is Susan Foreman. She was played by Carole Ann Ford and appeared alongside William Hartnell’s First Doctor when the programme began in 1963.

Susan is introduced in the first serial, “An Unearthly Child”, as a pupil at Coal Hill School in contemporary London. Her teachers, Ian Chesterton and Barbara Wright, become concerned because Susan seems extraordinarily knowledgeable about history and science while also making unusual claims about her home and family. Their investigation leads them to the TARDIS in a junkyard.

Susan is not simply an ordinary human teenager. She travels with the Doctor through time and space and displays an intuitive understanding of alien technology and historical events. The programme initially keeps the Doctor’s identity and Susan’s origins deliberately mysterious, helping establish the TARDIS as a gateway to a much larger universe.

Viewers sometimes confuse Susan with later companions such as Rose Tyler, Clara Oswald or Sarah Jane Smith. Those characters travel with different incarnations of the Doctor and are not his granddaughter. Susan is the defining family connection of the programme’s earliest stories.