Ooh an interdasting one...

Mammal: Cat (Easy)
Reptile: Chameleon (had to think about it, probably the coolest one to me tho)
Amphibian: Common Frog (Used to catch and release them along rivers as a kid. Theyre so tiny and fascinating)
Bird: Pigeon (its not something I think about often, but being out of the city for a while I miss the little guys. Besides, their cooing is cute, theyre very hardy and I love how they stick the middle feather to anti bird architecture. Goals)
Fish: Betta Fish (the most common fish we'd have as a kid rather than gold fish. Poor things deserved a lot more room but theyre very beautiful when theyre thriving in a proper enviornment)
Arthropod: Jumping Spiders (Simply adorable! Buggy Puppies)