Alexander Henry Fenwick Armstrong (born 2 March 1970) is an English actor, comedian, radio personality, television presenter and singer. He is the host of the BBC One game show Pointless, and is a weekday morning-show presenter on Classic FM.

Armstrong is a member of the comedy duo Armstrong and Miller. His television credits include Armstrong and Miller, Beast, Life Begins, Hunderby and Danger Mouse. He is also known as the voice of Mr Smith, Sarah Jane Smith's alien supercomputer in The Sarah Jane Adventures and the series 4 two-part finale of Doctor Who.

Armstrong is a bass-baritone singer and has released three studio albums.