Nicholas Courtney, best known for playing Brigadier Alastair Lethbridge-Stewart in Doctor Who, has died in London at the age of 81.
The series veteran passed away after a short illness, his agent confirmed to the BBC.
The series regular appeared on screen opposite a record five different Doctors and later worked with two other Doctors, David Tennant and Paul McGann, on Doctor Who audio stories.
In 2008 he reprised his Brigadier role in Doctor Who spin-off The Sarah Jane Adventures.
Courtney had already appeared in such series as Escape and The Saint before making his first Doctor Who appearance in 1965. To begin with he played a character called Bret Vyon.
In 1968 Courtney returned to the show to make his first appearance as the Brigadier opposite the second Doctor, Patrick Troughton.
The stalwart of the United Nations Intelligence Taskforce (UNIT) would periodically return over the next two decades before his final Doctor Who appearance in 1989.
After Doctor Who he landed parts in popular dramas such as The Bill, Casualty and Doctors.
In recognition of the 107 episodes he has appeared in, he became honorary president of the Doctor Who Appreciation Society in 1997. Courtney was a fan favourite.
Doctor Who writer Mark Gatiss remembered the actor as “a childhood hero and the sweetest of gentlemen.”