Nardole

Nardole is a fictional character created by Steven Moffat and portrayed by Matt Lucas in the long-running British science fiction television series Doctor Who. He is a companion of the Twelfth Doctor, an incarnation of the alien time traveller known as The Doctor, played by Peter Capaldi. In-universe, Nardole is a humanoid extraterrestrial being who serves as an employee to the Doctor's wife, River Song. He is killed by an alien and ends up as part of a cyborg body, but has his body rebuilt by the Twelfth Doctor. He becomes a full-time companion following the episode "The Return of Doctor Mysterio", and subsequently appears in his role as a companion and supporting character throughout the show's tenth series and then makes a cameo in the 2017 Christmas special "Twice Upon a Time". Lucas briefly reprised the role in a short written in support of the Black Lives Matter movement.

Nardole was originally a one-off comic relief character, but Lucas requested to come back to the series, with Moffat agreeing and bringing Nardole back. Nardole gained further character work as a result of the character's return, with the character now serving a more serious role within the series. Moffat designed Nardole to serve as a butler-like character who did not want to be the Doctor's servant. Nardole would frequently disagree with the Doctor, though the two grow to gain respect for each other as the series progresses. Lucas originally believed the character would return for only a few episodes, but that was soon expanded to re-appearances throughout the entire tenth series of the show.