"Armageddon It" is a song by the English rock band Def Leppard from their 1987 album Hysteria. It was released as a single in 1988 and went to No. 3 in the United States, becoming their fourth top-ten hit. It also reached the top 10 in Canada and New Zealand and the top 20 in Ireland and the United Kingdom.
The vocal style of the song is described as "T.Rex meets Eddie Cochran with backing vocals", according to lead singer Joe Elliott in the liner notes for Vault: Def Leppard Greatest Hits (1980-1995). There are two mixes of the song that appeared in the single: the "Atomic Mix", which is the album version, and the "Nuclear Mix", which is an extended version.