The Citadel: Prophecies

V: 447 - A Kraken

"Have you seen these others in your fires?" he asked, warily.
"Only their shadows," Moqorro said. "One most of all. A tall and twisted thing with one black eye and ten long arms, sailing on a sea of blood."

It's clear that this is a kraken, referring to House Greyjoy. The single eye, however, is suggestive of Euron Greyjoy, called Crow's Eye and always keeping one eye under a patch.