(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, No. 23 and No. 45.
The Ichor is a "Huge Creature", that walks slowly towards the player avatars. 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.