Complex sentence: The Ninth Doctor is the incarnation of the Doctor, the protagonist of the BBC television science fiction programme "Doctor Who" portrayed by Christopher Eccleston during the first series of the show's revival in 2005.
Split into simpler sentences: The Ninth Doctor is an incarnation of the Doctor, the protagonist of the BBC television science fiction programme "Doctor Who". He is portrayed by Christopher Eccleston during the first series of the show's revival in 2005.