premise: The Tenth Doctor appears in Journey's End.
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 . 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 .