Oliver Cromwell is a song released by Monty Python in 1989, and featured in their 1991 album Monty Python Sings. It is sung to Frédéric Chopin's Heroic Polonaise, and documents the career of British statesman Oliver Cromwell, from his service as Member of Parliament (MP) for Huntingdon to his installation as Lord Protector of the Commonwealth of England. The main lyrics are performed by John Cleese, accompanied by a small chorus comprising Eric Idle and other singers.

Oliver Cromwell is sung to the first ("A") section of the Polonaise, including the well-known main theme; it does not use the "B" section. The piano introduction is accompanied by a spoken-word introduction, setting a tone of macabre humour ("The most interesting thing about King Charles the First is that he was five foot six inches tall at the start of his reign, but only four foot eight inches tall at the end of it"), as are the subsequent connecting passages. All three instances of the main theme are given a tutti chorus followed by a recounting of the battles and other events of the period; sound effects are added, mostly sounds of battle and of horses. To the interlude is set King Charles I's trial and execution, with rubato adding atmosphere; the only sound effect is implied to be that of Charles's head falling (followed by a solitary giggle from Cromwell).