Which actor played the First Doctor in the original series?

William Hartnell played the First Doctor in the original Doctor Who television series. He introduced the character when the programme began on BBC television in 1963 and remained in the role until 1966.

Hartnell’s Doctor was an elderly, mysterious traveller with a sharp temper, a distrustful streak and a strong protective instinct. His first companions were his granddaughter Susan Foreman and her human schoolteachers, Ian Chesterton and Barbara Wright. This early group established the programme’s central pattern of combining historical adventures with journeys into the future.

Hartnell appeared in the first three television series and returned for the anniversary story “The Three Doctors”, broadcast in 1972–73. He left the role because of declining health, and the programme introduced the idea of regeneration so that Patrick Troughton could become the Second Doctor. Regeneration allowed Doctor Who to continue with a new lead actor while preserving the character’s identity.

Later productions have shown or recreated the First Doctor with other performers, including Richard Hurndall and David Bradley. Those portrayals do not change the canonical answer for the original series: William Hartnell was its First Doctor.