Doctor Who is a British science fiction television series broadcast by the BBC since
1963. The series, created by Sydney Newman, C. E. Webber and Donald Wilson,
depicts the adventures of an extraterrestrial being called the Doctor, part of a humanoid
species called Time Lords. The Doctor travels in the universe and in time
using a time travelling spaceship called the TARDIS, which externally appears as a British police
box. While travelling, the Doctor works to save lives and liberate oppressed peoples by
combating foes. The Doctor often travels with companions.
Beginning with William Hartnell, fourteen actors have headlined the series as the
Doctor; as of 2024, Ncuti Gatwa leads the series as the Fifteenth Doctor. The transition
from one actor to another is written into the plot of the series with the concept of
regeneration into a new incarnation, a plot device in which, when a Time Lord is fatally
injured, their cells regenerate and they are reincarnated. Each actor's portrayal is
distinct, but all represent stages in the life of the same character and, together, they
form a single lifetime with a single narrative.