Mentioned by Captain Singh during Episode 12 (Memorabilia) as not having had as many kills as Cicada. During previous seasons, we've had future villains referenced by someone before they've shown up. I can't remember who it was that actually mentioned him before his appearance; probably Thawne. We do know that prior to the Thinker showing up, he was mentioned by Abra Kadabra, and now we've had Singh mention Red Death. Season 5 will likely focus on the defeat of Cicada, and then further expand and explore the Thawne business, so Red Death, if he's going to feature, will be Season 6. In the comics, he's a twisted version of Bruce Wayne from a different Earth who goes a little insane (because he keeps losing his sidekicks) and merges with that Earth's Barry Allen in an attempt to settle the score with the Joker if I'm not mistaken. For some reason or other, instead of just going back in time and changing [his] past, I guess he ends up on Earth 1, and gets involved with this Earth's Barry Allen. Now, the likelihood the CW are going to allow any Bruce Wayne in the Arrowverse at the moment is unlikely, so the origin of Red Death (like Savitar) is going to be changed to accommodate their current structure. My question is, as both realistic and pessimistic as it may be; how are the writers going to screw up? In all seriousness, how do you suppose the character will be introduced if they're going to change his background? They can't do Evil Barry again, cause we've done that with Savitar, and they can't go Evil Batman (or Evil Bruce Wayne) because that's a persona they'll likely not want to touch on until WB give them the green light on allowing them to feature Earth 1's Bruce Wayne / Batman first. How are they going to go about this one?