Brigadier Alistair Gordon Lethbridge-Stewart was an integral part of the classic "Doctor Who" series, even appearing in the spin-off of the revised series that is currently enjoying popularity on the BBC.

Some even say that the characters influence was only bested by the actor who played him, Nicholas Courtney, who has shown over the years to have a deep affection and affinity for the many fans of the show. Sadly, Courtney passed away at aged 81.

Courtney, who was the longest running co-star of the series, died after a long fight with cancer. Tom Baker, who played the leading role on classic "Doctor Who" for some of its best years on the BBC, has expressed his sadness at his passing.

"Of all the characters in 'Doctor Who' there is no doubt he was the most loved by the fans for his wonderful portrayal of the rather pompous Brigadier," said Baker.

The actor made his first appearance on-screen in 1957, and later joined "Doctor Who" for the episode "The Daleks' Master Plan." He played Space Security Agent Bret Vyon in the episode. He later returned in "The Web Of Fear" as Col. Lethbridge-Stewart and then continued to appear in the series for years to come.

In 2008, he even appeared in an episode of "The Sarah Jane Adventures," re-uniting with Elisabeth Sladen who was also one of the Doctor's travelling companions while Courtney was part of the series.

Fans adored him and in 1997 he became the Honorary President of the "Doctor Who Appreciation Society," a position he is said to be proud to hold.

"Doctor Who" actor and writer Mark Gatiss has also expressed his sadness about hearing of the loss.

"A childhood hero and the sweetest of gentlemen," he said. "Splendid chap. All of him."