Devised by scriptwriter Terry Nation and designer Raymond Cusick, they were completely un-humanoid and like nothing that had been seen on television before.
The first (pilot) episode of the series, "An Unearthly Child", had to be re-recorded owing to technical problems and errors made during the performance.
During the days between the two tapings, changes were made to costuming, effects, performances, and the script (which had originally featured a more callous Doctor, and Susan doing unexplained things such as flicking ink on paper and folding it to produce a symmetrical pattern, and then tracing shapes over the pattern).
For more about the main character of the Doctor, see the The Doctor (Doctor Who).
Pages regarding individual Doctors and the various series and serials are linked in the List of Doctor Who serials.
When the show's budget was calculated, however, it was discovered that it was prohibitively expensive to re-dress the TARDIS model for each episode; The series' theme music was written by film and television composer Ron Grainer (who would later go on to also compose the theme to The Prisoner, among others) in collaboration with the BBC Radiophonic Workshop.