When you have been wandering the cosmos from one end of eternity to another for nearly a thousand years, what’s your philosophy of life, the universe, and everything? Doctor Who is 50 years’ old in 2013. Through its long life on television and beyond it has inspired much debate due to the richness and complexity of the metaphysical and moral issues that it poses. This is the first in-depth philosophical investigation of Doctor Who in popular culture. From 1963’s An Unearthly Child through the latest series, it considers continuity and change in the pictures that the programme paints of the nature of truth and knowledge, science and religion, space and time, good and evil, including the uncanny, the problem of evil, the Doctor’s complex ethical motivations, questions of persisting personal identity in the Time Lord processes of regeneration, the nature of time travel through ‘wibbley-wobbley, timey-wimey stuff, how quantum theory affects our understanding of time; and the nature of the mysterious and irrational in the Doctor’s universe.