My list is:
1. Platypus - cos they're unusual and amazing
2. Masked Owl - they're beautiful and I love the owls ability to fly soundlessly
3. Red Kangaroo - incredibly fast and strong
4. Echidnas (both species) - awesome defence mechanism
5. Taipan - world's most venomous land snake, obviously essential in my list lol
6. Koala - very cute, and amazing marsupial
7. Cassowary - fascinating bird and possibly the world's most dangerous
8. Kea - is endangered and the only true alpine parrot species in the world
9. Striped Possum - is very cute and is unfortunately endangered
10. Diamond Python - just cos I like them
11. Black-headed Python - one of only two python species in Australia (perhaps the world) that has no heat pits, and therefore feeds on cold-blooded prey, inc. other snakes
12. Birds of paradise (not referring to any particular species) - beautiful plumage, amazing mating rituals and generally very interesting birds
There's obviously a lot more I want to say, but as I'm restricted to 12....I'll just leave them in my head lol
