The Tenth Doctor, fearing his own mortality, travels alone between 2008-2010.
 The series depicts the adventures of a Time Lord called the Doctor, an extraterrestrial being who appears to be human
 In the 2013 episode "The Time of the Doctor", the Eleventh Doctor clarifies that he is the product of the twelfth regeneration due to a previous incarnation that he chooses not to count and one other aborted regeneration

