Dwarf elephants

"The drivers of the hathays, the carts pulled by the small elephants of Volantis, are marked with wheels."

- Varys

Dwarf elephants are a small species of elephant known to inhabit Volantis. They are used to pull hathays, carts pulled by slaves whose faces are tattooed with wheels.

In the books
In the A Song of Ice and Fire novels, dwarf elephants are only known to be found in Volantis, where they are a common mode of transport. Their skin is white and they emit a honking noise. Tyrion Lannister mistakes one of them for Illyrio Mopatis.