Reused Boss models/skeletons you've noticed.

[Eloah]

So, as with any game of FFXIV'S caliber, assets tend to get reused to save development costs. We see this a lot with our gear and some of the more basic mobs, a pallette swap here send there a slight name change and boom new item. But what about bosses? We tend to view the bosses as "unique" but there are cases when a boss has received a pallette swap, and uses the same skeleton as one we've encountered before.

I first paid more attention to this when I did Delubrum Reginae. I noticed that the third boss, Trinity Avowed's, movement looked familiar. Then someone pointed out it's using the original Shiva skeleton. That's not something you'd expect, especially since there are two Shivas in the game. So I'm curious what other bosses have you noticed shame their models/skeletons.

[Ilenya]

The first one I can think of that was super obvious was Coils T8.

[Valkyrie_Lenneth]

E10s is the 1st boss from the twinning. E9s is calistoferi from weeping city.

[MPK]

Ultimates but apparently that's still too much for the devs

[Ultimatecalibur]

I think it would be easier list the earliest appearance of a model/skeleton rather than trying to list out which skeleton/models each boss has.

[Bright-Flower]

Ultimates but apparently that's still too much for the devs

Ultimate wasn't delayed because of the models. It's how long the actual encounter design and balancing takes for Ultimate which is unrelated to asset reuse.

[Eloah]

E10s is the 1st boss from the twinning. E9s is calistoferi from weeping city.

I can see the similarities between the Twinning boss and the boss in E10, but I don't think the Cloud of Darkness and Calofisteri share a model. The Calofusteri mob is larger and floats more horizontally. I know a mob in Amaurot uses the Calofisteri model though, and I think the S rank in Kohlusia as well.

[TheMightyMollusk]

It may just be me, but I think Eden Ifrit is based on Diabolos with the wings removed, and Eden Garuda reminds me of Scathach. Which, I suppose, foreshadows their fusion (Raktapaksa/Diabolos Hollow).

[MariaArvana]

It may just be me, but I think Eden Ifrit is based on Diabolos with the wings removed, and Eden Garuda reminds me of Scathach. Which, I suppose, foreshadows their fusion (Raktapaksa/Diabolos Hollow).

nah, Eden Garuda's & Scathach's animation skeletons aren't even remotely close. Scathach's is used for pretty much any slim enemy model that holds some sort of spear and floats (Like Penithsilea in Eureka Pyros, and whatever the heck the add in A11 is called). If anything, ifrit is closer to Scathach, but he's also not using her skeleton. (it is similar to a wingless Diabolos though.)
Eden Garuda's skeleton is actually much closer or the same as Diabolos Hollow, as they have almost identical auto attack animations and extremely similar movement and idle animation.

Raktapaska literally uses Eden Ifrit's model & skeleton, only adding wings. (Watch his idle & auto attack animations.)

Pazuzu also uses the Diabolos Hollow skeleton
Omega is a re-skinned giant toad (watch the head movement)
Avatar from T8 is a reskinned Treant
Louhi is a reskinned Cruise Chaser
Demon Chardanook is a reskin of a wraith/phantom model
Chaos uses Sephirot's 1st phase skeleton
1st boss of Delubrum is a reskinned Ravana spliced with some Gilgamesh animations

E10 boss (on all fours) uses the same general 'behemoth' skeleton that's shared by tons mobs in the game.
While not an actual model swap, the E11 boss uses a huge amount of skill animations from GNB for its attacks (for obvious reasons)
All the SHB S ranks are re-skins of various bosses (Possibly the only exception being the Rak-tika one)

[Iscah]

All the SHB S ranks are re-skins of various bosses (Possibly the only exception being the Rak-tika one)

Rak'tika is the almost-a-boss "Ronkan Dreamer" from the first section of the Qitana Ravel.