What other kinds of mythological creatures would be cool in MLP?

We’ve already had griffons, a minotaur, a sea (river) serpent, and Cerberus himself. What else should make an appearance in the show?
 
My vote is sphinx for the win.

I wanna see some Sirens and Harpies.

Yata Garasu, Kirin, Tengu, Kraken, Demon Snakes, Giant Spiders, Nine-tailed foxes, Roc, hippogriff, Turul(Griffon King of Hungriffy/Gryphongary), Giant crustaceans, giant worms, wyvern, behemoth, Land of the Minotaur(Place), ice wolves, Yeti, kappa, oni, shadow ponies, snowy owl(literal), Jianshi Ponies(eastern vampire).

Sleipnir

A succubus pony (named Rarity)

Kelpie, Moon Bunnies, Leviathan, Thunderbird.

@SeraphimDawn
 
If you consider the comics canon, we already got giant spiders.
 
As for me, I’d like so see some Fearsome critters.

This as Discord’s pet
 
http://en.wikipedia.org/wiki/Wolpertinger
 
Or the jackalope.

Cthulhu or Azathoth.

Giants

@Dr Outback  
Giant Ponies you mean.
 
I’m hoping they would show a prehistoric form of those colourful equines.

@SeraphimDawn  
Of course Giant Ponies. Coming from the pony version of Jötnunn

Soviet ponies.

Cyclops. Bonus points if it’s Polyphemus.

Land Turtle(Literally)  
Sand Worms(literal)  
Scorpio  
Giant Ants  
Golem  
Slime  
Siren(Corrupt Sea ponies)

Cyclops ponies would be cool.

Mermares

Jack Frost Pony

I’d like to see some historical figures adapted to ponies in a way that would make it possible.

@Takuto_Devastated  
Beethovan  
Michelangelo  
Catherine the Great  
Marie Antoinette  
Teddy Roosevelt  
Trotsky

I’d love to see more Fae like creatures.

Medusa would make a pretty interesting villain.
 
Though a Gremlin would make great comic relief.
 
…
 
Both. The Medusa with the Gremlin as her generic less competent sidekick (i.e. Iago, Bartok… I’m sure there’s others)

A slit mouthed mare

@SeraphimDawn  
Don’t forget Jeanne D’arc and King Arthur!