(Unique game aspects not part of story canon)
The Ichor is a huge Orthrus featured in Resident Evil: Revelations 2's Raid Mode Online Events. Originally unique to Invasion of the Huge Creatures No. 6, Ichor returned for No. 12 the following year.
The Ichor is a "Huge Creature", that walks slowly towards the player avatars, alongside the Grue. The damage inflicted on the creature's enormous HP is accumulated through all the online players damage, making defeating them a cooperative effort between all Raid Mode players.