I think it was actually a collaborative project between Sydney Newman, Cecil Webber and Donald Wilson. But there were a whole bunch of people involved if I remember correctly.
Tony has the most correct answer first.
Sydney Newman is the single man generally credited with the creation of Doctor Who
, but it was very much a collaborative effort, and not only did Donald Wilson commission the report (on the feasibility of TV science fiction) that led to the creation of Doctor Who
in the first place, but it was Cecil Edwin 'Bunny' Webber who wrote up the original settings and character backgrounds of the series. The contribution of producer Verity Lambert shouldn't be discounted either, especially as she managed to overrule Sydney Newman on things like the theme music, or the Daleks, which he didn't like, and David Whitaker had a good contribution too.
Interesting fact: Originally, Webber wanted the Doctor to be a more malignant figure, trying to stop progress, and trying to go back in time to find an ideal past, and then nullify the future. He also suggested that the Doctor's biggest adversaries could be his own people, trying to stop the Doctor from doing this. Newman vetoed these suggestions straight away, preferring that the Doctor become a fatherly figure rather than a reactionary.
Okay, the floor's open.