Fire: Scorpion

Lightning: Raiden

Poison: Reptile

Ice: Sub-Zero

Smaug

Spyro

Poison: Taco Bell, Venom, My ex

If female poison, Medusa

Lightning:Toothless

Lightning:Thor

Black colored fire: Alduin

Deathwing

Torch (fire)

Voltage (lightning)

Butcher (blood)

Prism (crystal)

Avalanche (ice)

Viper (venom)