Urzen

Urzen is a background character in the second season. He is played by an unidentified extra and debuts in "The Ghost of Harrenhal" though first identified in "Valar Morghulis". Urzen is an ironborn raider and member of the Sea Bitch crew.

In the books
In the Song of Ice and Fire novels, Urzen's background is the same. He is among the ironborn who raid the Stony Shore and part of the force that captures Winterfell. Urzen is among those who abandon Theon when the Northmen arrive to retake Winterfell.