Alun Armstrong is a prolific English character actor.

Armstrong grew up in County Durham in the north-east of England. He first became interested in acting thanks to Shakespeare productions at his grammar school. Since the start of his career in the early 1970s, he has, by his own account, played "the whole range of characters — from the grotesque to the musical... I always play very colourful characters, often a bit mad, despotic, psychotic".

Among his many works are six different adaptations of Dickens and seven seasons as the eccentric former detective Brian Lane in the series New Tricks.

Armstrong is also an experienced stage actor who spent nine years with the Royal Shakespeare Company. He was the first to play the role of Thénardier in the London production of Les Misérables and won the Laurence Olivier Award for his performance in the title role of Sweeney Todd.