"This Corrosion" is a song from the album Floodland by The Sisters of Mercy. It was released as a single in 1987 reaching number 7 in the UK Charts.
The song was written by Andrew Eldritch, and produced by Jim Steinman. It is generally recognised as one of the band's most well-known songs, using a 40-piece choir, with the LP version of the song lasting for nearly 11 minutes (the single versions are substantially shorter). Eldritch's lyrics concern his previous band members leaving The Sisters of Mercy to form The Mission.
The track was featured in the 2013 (sci-fi action comedy) film, The World's End, with star Simon Pegg playing a 40-something who had been a "goth"/alternative rock fan in the 1980s as a youth and one who still styled himself on The Sisters of Mercy front man, Andrew Eldritch. The 7" version/single edit (4:27) appears on the soundtrack to the film.