Elephants

"The slaves that collect the dung of horses and elephants are marked with flies."

- Varys

Elephants are very large mammals native to Essos. They are commonly used for carrying goods and people over great distances. In Volantis, slaves who are tasked with collecting the dung of elephants and horses have flies tattooed on their faces. There is a similar but smaller species known as dwarf elephants.

In the books
In the A Song of Ice and Fire novels, elephants are found throughout the Free Cities and are not native to Westeros. They inspired the names of the Isle of Elephants in the Jade Sea and a party of the triarchs.

Elephants are commonly seen in Astapor carrying latticework litters on the backs. Daenerys Targaryen acquires three of them when she takes the Great Pyramid and they remind her of hairless mammoths, though with bobbed and guilded tusks and sad-looking eyes. She later sees one kill a pack of six red wolves in Daznak's Pit. In Volantis, they have the names of would-be triarchs painted on their sides during elections. Tyrion Lannister sees one for the first time in Old Volantis and cannot help but stare at it. The armies of New Ghis makes use of elephants, as do the Golden Company. They are also a game piece in cyvasse.