* AuthorsSavingThrow: The developers explained that the reason why Crimson Heads were not included in ''Resident Evil Zero'', after being retroactively introduced in the ''[[VideoGame/ResidentEvil1 REmake]]'', is because Rebecca and Billy don't spend as much around the same place as Alpha Team does in the ''[=REmake=]''.
* DemonicSpiders:
** The leech zombies, without a shadow of a doubt. Tough as nails with an insanely long reach, they cause considerable damage when they hit, and when they die, they ''explode'' for even more damage. Luckily, [[KillItWithFire fire kills them]] fairly quickly, mitigating the annoyance a bit.
** Eliminators are small, soak up more damage than they have a right to, attack in packs, and like dodging bullets.
* EnsembleDarkhorse:
** Despite the fact she's the focal character of the game, Rebecca is one as far as the series itself is concerned. Fans of her were more than pleased to see her get her own game and hope for more in the future.
** Billy. So much to the point fans desperately want Creator/{{Capcom}} [[spoiler: to reveal his fate.]]
* EvilIsSexy: The young James Marcus seems to have been invented for the sole purpose of adding more {{bishonen}} to the series.
* FanonDiscontinuity: Fans who don't like ''[[VideoGame/ResidentEvilGunSurvivor Resident Evil: Survivor]]'' have been known to use the ContinuityNod to declare ''Resident Evil Zero'' non-canon.
* GoddamnedBats: Actual bats, too!
* HilariousInHindsight: The submachine gun that's unlocked after beating the game with either an S or A rank on Normal or Hard mode strikingly resembles the SIG-Sauer MPX, which was released approximately 13 years after the game.
* InferredHolocaust: One [[WildMassGuessing possible reason]] [[spoiler:Billy]] didn't show up in later games? The last you see of him is him walking into a forest infested with man-eating monsters, unarmed.
* {{Narm}}: It's ''Resident Evil''. [[Narm/ResidentEvil What did you expect?]] Special mention goes to [[spoiler:Dr. Marcus]] controlling his leech doppelgängers through a countertenor opera solo.
* ScrappyMechanic:
** Unlike previous games, there are no crates for you to store your stuff in. Instead, the inventory system here works by having Billy and Rebecca ferry stuff you need from one area to the other.
** Rebecca is disgustingly frail. While this may have been intentional to put more emphasis on Billy being the fighter of the two, there's a difference between can't take much punishment and "three Eliminator attacks send Rebecca into orange caution status". It's frustrating using double the healing items necessary if you're not careful; but the game also has aforementioned Eliminators and leech zombies who are hard to avoid regardless.
* VindicatedByHistory: ''Resident Evil Zero'' had to compete with being released after the ''[=REmake=]'', which considering the incredible reception to that game, was no easy task. It also introduced a lot of new features like the partner system and lack of item boxes, and both were disliked by just about everyone. With the HD re-release of the game, however, a lot of detractors to the game have been much kinder to it, and have stopped comparing it to ''[=REmake=]''. It's now regarded as a flawed, but ultimately entertaining and unique entry in the series.
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