Silence

Silence is an ironborn longship captained by Euron Greyjoy.

Background
Euron left the Iron Islands years ago, and became the terror of the world's oceans, raiding ships from Oldtown to Qarth.

Euron's ship was once caught in a storm on the Jade Sea, far east of Qarth, during which Euron lost his mind: the crew had to tie him to the mast so he wouldn't jump overboard. After the storm had passed and they untied him, he personally ripped out the tongues of his entire crew. When nonchalantly recounting this event years later, he glibly explained "I needed silence" - hence the new name of his ship, for its crew of mutes.

Aboard the Silence, Euron has raided ships from all the Free Cities and across the Summer Sea, including Summer Islander ships and even Ibbenese whaling ships. During this time Euron and the Silence frequently visited the pirate dens of the Basilisk Isles, to sell plunder and take on new provisions.

Season 6
Euron returns to the Iron Islands, and confronts his older brother Balon Greyjoy on a rope bridge of Pyke castle during a violent storm. Balon recounts the story her heard about Euron losing his mind and cutting out the tongues of his entire crew, which Euron calmly admits to. When Balon realizes that Euron has come to kill him they get into a brief scuffle before Euron throws his brother over the side of the bridge to his death.

In the books
Euron's private dungeon is located below the decks of the Silence. Within it he is fond of cutting pieces off his prisoners and then force-feeding their own body parts back to them. He also has an almost obsessive need to personally cut the tongue out of the mouth of every new crewmember or prisoner he acquires.

For as yet unclear reasons, Euron is also capturing priests from all of the world's religions and holding them prisoner aboard the Silence, torturing them. From a preview chapter from the sixth novel, Euron apparently attempts to use them all as human sacrifices in a mass ritual which will usher him is as a dark messiah of sorts for whatever dark powers he may or may not be in league with. Euron manages to capture his own brother Aeron Greyjoy right after the Kingsmoot and hold him prisoner about the Silence as it advances south to Oldtown, during which time he force-feeds him Shade of the evening, giving Aeron a distorted, psychedelic vision of what Euron intends, part of which involves Euron seated on the Iron Throne with a dark woman at his side.