Creatures not seen on Pandora

[tm20]

Medusas (giant floating jellyfish like creatures)


Dinicthoid which is a 2m long fish with a massive and powerful jaw


the thing that gave Quaritch his scars (forgot what it's called, starts with "S" and it's not the slinger)

[ftxey Keye'ung]

The Medusas is described in the ASG as being quite dangerous..floating around above the tree's with it's deadly and implacable tentacles sweeping the canopy or ground below.

EEK!

[Harrie]

There are 22 species in the Activist Survival Guide, including the Na'vi.
The ones seen are Na'vi (of course), Arachnoid/Kali'weya (on a tree during the first mission to the jungle), Glow worms (in a deleted scene I think?), Anemonoid (in the water), Tetrapteron, Ikran, Direhorse/Pa'li, Fan Lizard, Toruk, Titanothere, Hellfire Wasp (when the Pa'li are feeding), Hexapede/Yerik, Prolemuris, Stingbat (in the distant, flying in the jungle), Sturmbeest (deleted scene), Thanator/Palulukan, and Viperwolf/Nantang.
Perhaps some more, because I haven't seen the deleted scenes.

seen in the movie but NOT in the survival guide: Tapirus (check on the Avatar Wikia)

[Manne]

the thing that gave Quaritch his scars (forgot what it's called, starts with "S" and it's not the slinger)

It's called a "Slinth" and its apparently like a Tiger. but I can't find any information on it.

~Manne