The Headless Horseman is an alternate boss, capable of replacing any of the Harbingers, thus making him a boss that may be encountered more than once in one playthrough. It resembles the other horsemen, although his head is detatched and has no jaw, one eye and a piece of flesh missing underneath its missing eye. The body looks rotting and diseased, though it holds onto the horse. The horse has an actual horse's head instead of a skull.
The Horseman combines all the abilities of the other horsemen, excluding Conquest:
- Like War, his head can charge through the screen several times and chase you.
- Like Pestilence, he will fire bombs at you which leaves a puddle of damaging red Creep.
- Like Famine, the head is capable of firing three shots at you.
- Like Death, there are two enemies that must be killed in order to achieve victory.
Be careful not to get rammed by the separated head. It will always fly through the screen in the same pattern: Upper portion, middle portion, and lower portion of the screen. Explosions might change the path of the head. An idle head will occasionally spit bullets at you, so don't ignore it.
The body moves around the battlefield and shoots IPECAC like bullets at you. These deal splash damage and leave a damaging puddle of Creep on the floor. These puddles can severely limit your movement and thus prove problematic. You might want to keep in mind that those explosions caused by the projectiles can change the head's trajectory as well. Because this boss can appear in early floors, he is a dangerous boss at all times.
The order in which to take out the bodyparts is really just a matter of taste. Once a part of the duo has been eliminated, the other part seemingly loses its advantage over combat.
Eternal Headless Horseman's head shoots blood shots in a single, rapid burst, much like machine gun. The head slowly regenerates HP, leaves creep at 50% of its HP and remains the ability to charge through screen. The body however, shoots more IPECAC bombs that leave creep.
- The Headless Horseman cannot damage himself with his own explosions or charging.
- Killing the different body parts in a specific order does not increase the chance of a specific collectible being dropped.
- A Pony cannot be re-rolled unless picked up first.
- Multiple heads may also appear as common enemies in Sheol and Utero. Single heads can be found in Necropolis.
- A single head might be found in Necropolis in a room with spike traps, and can be easily defeated by dodging the charging head and waiting for it to charge into the spikes.
- According to Edmund, it is possible to find a champion version of the Headless Horseman, but it's extremely rare.
- However, this is actually incorrect, and no champion version of The Headless Horseman exists in the game.
- Once the player acquires the White Pony, the stickhorse of the Headless Horseman will change its color to white as well. This, however, is a purely cosmetic change.
- The Headless Horseman is a fictitious, mythological character, originating from folklore of the European middleages. The best known example of the Headless Horseman is the Irish dullahan, but there are many local variations of this figure. Today, the Headless Horseman is a staple in many fantasy games.
- Before the battle begins, the Headless Horseman will bear the name "Headless Horsemen." It is simply a typo.
- The headless horseman is missing his jaw. This is also the same with Daddy Long Legs and The Blighted Ovum
- If you die by the trail of damaging creep from his bombs, it's displayed as if you've been killed by a Brain. (see picture in gallery)
- This can happen with any type of creep.
- Defeating this boss in the Caves or Catacombs will unlock the "Little C.H.A.D." secret (normally for defeating C.H.A.D.).
- The Headless Horseman occasionally replaced Satan as the boss of Sheol. This bug has since been fixed.
- Due to delay, the Headless Horseman can fire 6-8 shots, similar to Pestilence.