Doctor Who
Thirteen actors have headlined the series as the Doctor. The transition from one actor to another is written into the plot of the show with the concept of regeneration into a new incarnation, a plot device in which a Time Lord "transforms" into a new body when the current one is too badly harmed to heal normally. Each actor's portrayal is unique, but all represent stages in the life of the same character. Together, they form a single lifetime with a single narrative. The time-travelling feature of the plot means that different incarnations of the Doctor occasionally meet. The Doctor is currently portrayed by Jodie Whittaker, who took on the role after Peter Capaldi's exit in the 2017 Christmas special "Twice Upon a Time".
Adric
Adric is a fictional character played by Matthew Waterhouse in the long-running British science fiction television series "Doctor Who". He was a young native of the planet Alzarius, which exists in the parallel universe of E-Space. A companion of the Fourth and Fifth Doctors, he was a regular in the programme from 1980 to 1982 and appeared in 11 stories (40 episodes). The name Adric is an anagram derived from Nobel Prize-winning physicist Paul Dirac. Waterhouse is the youngest male actor to play a companion so far in the series.