Editing Logopolis (section)

===Casting===
{{multiple image |total_width=350 |perrow=4 |caption_align=left
| image1 = Peter Davison 2016.jpg
| caption1 =[[Peter Davison]] (The Doctor)
| image2 = Janet Fielding, Baltimore 1987 2.jpg
| caption2 = [[Janet Fielding]] (Tegan Jovanka)
| image3 = Sarah Sutton.jpg
| caption3 = [[Sarah Sutton]] (Nyssa)
| image4 = Anthony Ainley, Baltimore 1987 2.jpg
| caption4 = [[Anthony Ainley]] (The Master)
| footer = Actors joining the regular cast of ''Doctor Who'' in ''Logopolis''
}}
The serial introduces Janet Fielding in the role of Australian trainee [[flight attendant]] Tegan Jovanka. Nathan-Turner conceived the role in collaboration with Bidmead, with the intention of introducing a younger female character who would display a superficial self-assurance masking inner vulnerability, without returning to the stereotype of screaming female companions of earlier serials. Brisbane-born Fielding had lost some of her native [[Australian accent]] since emigrating to the UK in 1977, but revived her accent to audition successfully for the part.{{sfn|Anghelides|Richards|1994|pp=6 & 9}} Nathan-Turner initially wished to reintroduce a former companion to provide continuity for viewers following Baker's regeneration, but created Tegan when [[Elisabeth Sladen]] ([[Sarah Jane Smith]]) and [[Louise Jameson]] ([[Leela (Doctor Who)|Leela]]) both declined to return for the duration of [[Doctor Who season 19|season 19]].<ref>{{cite AV media notes |last1=Pete |first1=McTighe |author-link1=Pete McTighe |date=2019 |chapter=Logopolis |title=''Doctor Who'': The Collection Season 18 |publisher=[[BBC Studios]] |page=23}}</ref>

Two cast members returned from the previous serial, ''[[The Keeper of Traken]]'': Sarah Sutton reprised her role as Nyssa, joining the TARDIS crew as a companion; and Anthony Ainley had his first full exposure in the role of the Master, a part he would continue to play for eight years. Outwardly, Ainley's beard and dark costume suggested close continuity with [[Roger Delgado]]'s portrayal in the early 1970s, but Ainley imbued his part with a greater focus on revenge and blackmail.{{sfn|Anghelides|Richards|1994|pp=4,12-13}}

The part of the mysterious Watcher was played by Adrian Gibbs; his part was left uncredited in order to foster a belief among fans that Peter Davison had played the role wrapped in white fabric. In fact, Davison's only appearance was during the final seconds of Part Four as the newly regenerated Doctor, for which he attracted a full actor's fee.{{sfn|Anghelides|Richards|1994|p=4}}