Cases of monsters being used outside their native IWADs

[Jimmy]

Very occasionally, perhaps more often when you play a lot of ZDoom mods like I do, you'll run into monsters outside their usual IWAD habitat - say, Heretic enemies in Doom, or vice versa. I'm not talking about the randomizer mods that include everything, by the way - I'm talking maps/mapsets that deliberately use these monsters for a certain purpose.

 

Perhaps the best example of a WAD that pulls off this very effectively is Mike "Cyb" Watson's Void, which uses Afrits, Dark Bishops and the Heresiarch from Hexen in a Doom map for ZDoom, a port that has enabled mappers to place monsters from any supported Doom engine game into a map, so long as sprites and sounds are provided. I give a subtle nod to this WAD with the inclusion of Dark Bishops in my Boom mapset realms of ZO0N - thanks to Obsidian's DEHACKED wizardry there, since PrBoom(+) doesn't have the capabilities of cross-IWAD monster usage that ZDoom does.

 

Certain monsters from Realm667 are reskins of Heretic/Hexen monsters - at least, now using their own DECORATE definitions to make them unique monsters instead of literal resprites (although as I recall they did exist as such at one point). The Soul Harvester for example is functionally identical to the Heretic mummy (right down to the rising spirit effect that occurs when you kill it), and the Hell Warrior is similar to the Hexen slaughtaur. Both these monsters in their original incarnations can be found in the ZDoom Community Map Project Take 1.

 

Hordes of Chaos X, a Heretic mapset, uses a slew of textures, decorations and of course enemies from both Doom and Hexen across its 25 levels. This results in a highly unique gameplay experience.

 

It only struck me today that I'm really fond of this being done. Are there any other instances, well-known or not, of this?

[scifista42]

ZDoomWars is a multiplayer mod where each player class corresponds to one of several IWADs and you spawn monsters from your class's IWAD and they (with your ally's monsters) fight against your opponent's monsters, so if everybody in a particular game chooses a different player class, the result is quite a mashup.

[Cruduxy Pegg]

The avatar (Red heresiarch) and those shielded undead knights -shudders- immediately come to mind as borderline overused. Thankfully centaurs and stalkers rarely make it out of hexen into other iwads!

[galileo31dos01]

I think, Survive in Hell uses a magician similar to the Disciple from Heretic, but apparently it can walk. Also in Deus Vult II there's the cleric from Hexen used as an enemy. A month ago I saw a pair of megawads that uses Heretic monsters replacing some of the Doom's monsters sprites, Herian 1 and 2 were their names, though the first one seems to have bad reputation. 

[leodoom85]

Neodoom uses the ophidian. the reiver, the wyvern and the chaos serpent...Also, there's Resurrection of Chaos (ROC) for Hexen which is a sort of "jokewad" and uses monsters from Doom...