When you browse his imdb.com profile, it's striking how often he played a military character. Typecasting? Or was he just very, very good at it?
He might have been just one of those actors whose face keeps popping up in TV drama and sitcoms, if it hadn't been for his long-running part in Doctor Who as Brigadier Alastair Gordon Lethbridge-Stewart.
He first appeared in 1968's The Web of Fear alongside Patrick Troughton. So popular was his character that he made numerous returns, both in the original series and in spin-offs; the IMDB lists 107 episodes of Who alone. He played the Brigadier in The Sarah Jane Adventures as late as 2008. Only a handful of soap opera actors have played the same character for that long.
It was during the Third Doctor's exile on Earth, with the Doctor working alongside UNIT, that the character really came into his own.
The friendship and freqent arguments between the Doc and the Brig were one of the elements of the Third Doctor's reign that made it, for me, so unique, special and great.
There are a lot of Brigadier tributes on YouTube, because he is so well-loved. Here's a UNIT one I liked.