premise: The Tenth Doctor spends time traveling alone.
hypothesis: The Tenth Doctor is an incarnation of the Doctor , the protagonist of the BBC science fiction television programme Doctor Who , who is played by David Tennant in three series as well as nine specials . In the programme 's narrative , the Doctor is a centuries-old Time Lord alien from the planet Gallifrey who travels in time in his TARDIS , frequently with companions . This incarnation 's companions include working class shop assistant Rose Tyler ( Billie Piper ) , medical student Martha Jones ( Freema Agyeman ) , and fiery temp worker Donna Noble ( Catherine Tate ) . He eventually parts ways with them all by the end of the 2008 series finale , `` Journey 's End '' , after which he attempts to travel alone for the duration of the 2008 -- 2010 specials before being accompanied by Donna Noble 's grandfather Wilfred Mott on his final adventure in The End of Time .