Coffin was a great character whose story only ran in four issues of Eerie, when for me, he could've easily gone on much longer. He belongs to the sub-genre of Weird Western, as more-or-less begun by Jonah Hex, and still going strong these days in excellent series like Billy The Kid's Old Timey Oddities.
He's a nameless bad guy cursed with immortality and looking for redemption, though as you'll see, as this is a Warren series hero, immortal doesn't mean invincible.
Because he's drawn by Jose Ortiz, Coffin is a walking pile of pulped flesh, every wound and torment visible. And because he's written by Budd Lewis, he's not particularly likeable and is in fact barely a hero at all.
When the 'Eerie series heroes' first began, the avowed intention was to stand out from Marvel & DC's characters, by ensuring that each series would come to a definite end, and each hero could, and often would, die.
Coffin goes a couple of steps further than that. It doesn't matter how hard he tries to redeem himself, he's already in Hell.
Here's the first two episodes.