| Spoiler warning!|
This article contains plot details about later parts of the game.
Elsens are the main NPCs of OFF and are found in all zones, except Zone 0.
Elsen, for the most part, live only for their work. Several remark that those who contribute significantly in some way may be immortalized by having a train station named after them. No Elsen are ever named in-game, but the stations Damien, Pentel, Alma, and Shachihata appear in zone 1.
Elsens are vaguely human-like characters (that have been confirmed as human by Mortis Ghost) with large eyes and a square-shape head. All Elsens wear ties, including the Miner Elsens found in Zone 1. They breathe smoke and live on a diet comprised mostly of meat. They are mainly characterised as shy, and their distinct audio is a 'hhh' sound that sounds relatively like breathing, and increases in pitch (or lowers, as is the case with the Critic and Pastel Burnts) just before an Elsen becomes a Burnt.
When put under pressure, Elsens transform into a different, agressive form known as a Burnt. Burnts at first look like Elsens, except their heads are replaced by a pillar/spout of black substance, which is generally thought of as blood. However, further on into the game, Burnts begin to deviate more and more from human-looking, the Burnts in Zone 3 looking almost reptilian.
In Zone 3, Elsens are shown to need sugar, an addictive material and the so-called 'fifth element', in order to keep them happy and stop them from going insane. When in sugar-deprivation or in danger of losing their sugar, Elsens become even stranger and more dangerous Burnts. It is revealed that Elsen corpses are the primary ingredient in sugar.
- The Elsens were voiced by Alias Conrad Coldwood himself. Their signature gasp is the first track in the original soundtrack entitled "Global."
- Elsens are all male and unable to reproduce, as said by Mortis here. This does raise some questions about where Elsens come from.
- A single Elsen can be found in Zone 2 after being purified. Along with Zacharie, the Secretaries, potentially Sugar if you didn't kill her, and either The Batter or The Judge (depending on which ending you took, not including the Space Apes ending), this Elsen is one of the only characters alive at the endgame.
- The idea of Elsen corpses being used as food (in this case, sugar) probably comes from the film Soylent Green, where due to a lack of food, the government collects bodies and produces a nutritious substance to satisfy the population.