Is Doctor Who science fiction?

Answer 1

Yes.

To expand: while there is a faction of Science Fiction fandom that has very strict rules on what constitutes "real" science fiction (everything else falls into either "science fantasy" or, worse, "space opera"), Doctor Who has been featuring stories built around real scientific concepts - including time travel - since it began in 1963. Recent seasons have touched on scientific concepts such as uploading of consciousness, Artificial Intelligence and "flesh avatars", to name just three. To be sure, Doctor Who has had a few "space opera"-style storylines in its long history. But it can correctly be defined as science fiction due to the huge number of science-based or science-inspired stories produced over 48 years.

Answer 2

If you are referring to the Doctor, he comes from the planet Gallifrey in the constellation of Kasterborous
Doctor Who, comes from the destroyed Timelord planet, Gallifrey. Gallifrey was destroyed in a giant war, but has surfaced a few times through out the show through time travel and other complicated means.

Answer 3

No he comes from Gallifrey. In The Runaway Bride, Donna continually calls him a Martian, to which he always says:" I'm not from Mars." He's a Time Lord!