The Doctor (Doctor Who) credits Tennant as "Doctor Who". The credit reverted to "The Doctor" for 2005's Christmas special "The Christmas Invasion" and all subsequent stories at Tennant's request. Matt Smith, Peter Capaldi and Jodie Whittaker have continued to be credited as "The Doctor". John Hurt plays a mysterious past incarnation of the Doctor in the 50th anniversary special "The Day of the Doctor", with minor roles in "The Name of the Doctor" and mini-episode "The Night of the Doctor", created as a "mayfly Doctor" by Steven Moffat. In the television episodes, he is credited as "The Doctor", but he is introduced as "The
First Doctor or even whether their exile is self-imposed. It would not be until the last adventure of the Doctor's second incarnation that the name of the Doctor's people (the Time Lords) would be revealed, and the third incarnation before the name of his home planet (Gallifrey) was first spoken. The series' first episode opens with a pair of schoolteachers in contemporary (1963) London, Ian Chesterton and Barbara Wright, investigating the mystery of Susan, a student who seems confused and even frustrated at how what she is learning in history and especially mathematics seems to be wrong. Following Susan to her supposed