Michael Sheard

Michael Sheard appeared in Doctor Who on six occasions. He had links with other Sci-Fi and 'Cult' genre projects - and he attended a great many conventions and signings thanks to these. He died in 2005, at the age of 67. He was a persistent champion of Doctor Who for many years.
He was born in Aberdeen, Scotland, in 1938, and learnt his stagecraft at RADA. His first Doctor Who was The Ark in 1966 - playing the doctor, Rhos, in episode 2 only.

His next appearance was as another physician - Dr. Summers, the Stangmoor Prison doctor - in The Mind of Evil (1970).
After this he delivered his most significant performance in the programme as the tragic Lawrence Scarman in The Pyramids of Mars (1975). Unable to believe his brother is dead, and has had his corpse reanimated by Sutekh, he tries to reason with him - but is murdered for his efforts.

He made one further appearance alongside Tom Baker's Doctor in The Invisible Enemy. In this, he was Titan Base supervisor Lowe, who gets taken over by the alien Swarm.

A clone of Lowe is destroyed by the anti-bodies in the Doctor's body, whilst the real Lowe perishes back on Titan.
For his fifth appearance in the programme - alongside the fifth Doctor - Sheard was back in physician mode. He's the town apothecary, Mergrave, in Castrovalva.

His final Doctor Who appearance was in 1988's Remembrance of the Daleks, in which he played the unnamed Coal Hill School headmaster who has been taken over by Davros' Imperial Daleks.

This was obviously a nod to his most famous British TV role - the scourge of the BBC's long-lived school-based children's drama Grange Hill. He played the rather humourless, be-wigged, Mr Bronson - the man we all loved to hate.
Outside Doctor Who, Sheard found himself the go-to person when anyone wanted an Adolf Hitler. He played the part five times.

His highest profile Fuhrer was actually only a brief appearance - a cameo in the book burning scene in Indiana Jones and the Last Crusade, but he also played him in ITV's somewhat feeble attempt to emulate Doctor Who, The Tomorrow People. As well as Hitler, he also played Heinrich Himmler - and Hermann Goering.

If there was one role that landed him all those conventions and signings, it was his contribution to the Star Wars saga. Again only a brief appearance, he's the hapless Admiral Ozzel in The Empire Strikes Back - who gets throttled via the Force by Darth Vader for being ever so slightly incompetent.
A couple of other genre roles worth mentioning are Space 1999 (Dragons Domain), The New Avengers (Faces), Beasts (The Dummy) and Blake's 7 (Powerplay).
One of his last roles was as narrator for a Star Wars fan-made project. He contributes to one Doctor Who DVD commentary, and appears in the making-of documentary, for Pyramids of Mars. Do check it out. I have little doubt that, had he lived, he would have turned up in the new series at some point - maybe making his sixth Hitler performance... Michael - we salute you.