"Redshirts" is a song by Jonathan Coulton, a singer/songwriter most famously known for creating Still Alive, and Want You Gone, from the Portal series. "Redshirts" was written to accompany the book of the same name, written by John Scalzi. It is about the hardship faced by a Star Trek character, labeled by their redshirts, who die in every episode.
References
Redshirts (song) Wikipedia(Text) CC BY-SA