Alexander Armstrong (born 2 March 1970) is a British comedian and actor.

Sir Alexander Armstrong (1818 - 4 July 1899), born Donegal, Ireland, was a naval surgeon, explorer, and author who from 1850-1854 sailed the arctic on HMS Investigator under the command of Robert John Le Mesurier McClure in search of the lost expedition of explorer Sir John Franklin. His account of the voyage, Personal narrative of the discovery of the north-west passage, was published in London in 1857.