There are a lot of creatures fortnite has added over the years but there are quite a few missing from creative/uefn.
It seems the most wanted are the Chapter 2 Cube Monsters and Caretakers.
But here are some others that have yet to make it to the game that should:
Loot Sharks
Klombo
Alien Parasites
Bud the Mushroom
Crows
Zombie Chickens
Jumpscare Zombies (soccer skins)
Alive Llama
Gold Chicken
Chapter 2 Raptor (Variant)
Underworld Wolf
The Puppeteer
Queen Bug (heavily requested by people)
Cattus
Bud the Mushroom
Dark Voyager Drones
Along with these we should be given the setting to allow creatures, that support this, to have items in them like they could in Br and stw.