What I am referring to here is: Songs in which the lyrics clearly indicate that the person singing the song is either already dead or is in the process of physically dying as the song is being sung. Some examples are:
“Long Black Veil”, in which the singer has been dead for about ten years;
“I Started a Joke” by the Bee Gees (“Till I finally died…”);
“Your Flag Decal Won’t Get You Into Heaven Any More” by John Prine (in the final verse of which the titular phrase is spoken to the protagonist by St. Peter).
I would also include “El Paso” by Marty Robbins and “D.O.A.” by Bloodrock, as in both cases the singer is obviously toast. But “I’ve Gotta Get A Message To You” by the Bee Gees is right out, because the guy’s got a whole hour to go.
One borderline category that I’m excluding is songs sung by historical figures who are dead (e.g., “Nostradamus” by Al Stewart). Although Nostradamus is long dead, the lyrics don’t state that he is dead at the time he is singing the song. (I hope this makes sense.)
Procol Harum, “The Dead Man’s Dream”
Grateful Dead, “Black Peter”
Roy Harper, “Don’t You Grieve” (about Judas: “My name is Jude Iscariot, and my home address is Hell”)
Most of the Black Parade album by My Chemical Romance, sung from different characters that are either dead or dying. While several of the deaths are not even mentioned (so technically they might still be alive,) once you know the theme of the album, most of the rest of the songs are pretty obvious. The most blatant example is the album opening tracks, which really should be played together, Famous Last Words and Dead!. Famous Last Words even tells you right from the start that for the rest of the album you will be seeing things from the viewpoint of various dead characters.
Iron Maiden - Hallowed Be Thy Name, a prisoner about to be executed by hanging
Metallica - Ride The Lightning - a prisoner in the electric chair
Led Zeppelin - Gallows Pole
Two other possibles if you are including Suicide -
Adams Song - Blink 182
Metallica - Dyer’s Eve
Though it’s not perfectly clear to me if the singer is actually dead or if it’s a “live” account of his dead, the lines “Then I saw black, and my face splashed in the sky” suggest that it’s sung from a dead man’s perspective.