Mord

Mord is a recurring character in the first season. He is played by guest star Ciaran Birmingham and debuts in "The Wolf and the Lion." Mord is the turnkey at the Eyrie. He is rewarded by Tyrion Lannister with a pouch of gold when he assists Tyrion in winning his freedom from the cells.

Background
Mord is the gaoler in charge of the sky cells in the Eyrie. He is in the service of House Arryn. He is slow witted and cruel.

Season 1
Tyrion Lannister is given into Mord's redoubtable care whilst a prisoner at the Eyrie. While Tyrion is trapped in the Sky Cells he tries to bargain for his freedom. Mord responds by beating him because he has no money to pay with. With great difficulty, Tyrion manages to bargain with Mord to allow him a fair hearing with Lysa Arryn, under the promise "a Lannister always pays his debts". Tyrion is able to manipulate the situation during his audience with Lysa to demand a trial by combat, which is won in his favor by Bronn. Set free, Tyrion asks for his money-purse back from Rodrik Cassel. As Tyrion turns to leave, true to his word, he tosses the gold-filled purse to Mord, much to Mord's delight.

In the books
In the Song of Ice and Fire novels, Mord is a petty, cruel man who delights in tormenting prisoners and telling them how they are going to fall out of the cells to their deaths on the rocks thousands of feet below the castle.