R.O.D. - The TV:

The head of the British Library Special Operations Unit and Yomiko's former boss. He took control of the organization after the death of the Gentleman and is now often referred to as "Mr. Carpenter." His face seems a bit more lined from stress (and, possibly, age), and he now walks with the assistance of a cane. As always, Joker smiles all the time and initially appears as calm, reassuring, and easy-going as ever, but as the series progresses he gets more violent and high-strung, revealed to be an elitist who holds the same "human selection" principles as the I-Jin (the villains from the OVA). Disappointed by the decline of British global influence following the Gentleman's death, Joker implements a scheme to regain control of the world, no matter the human cost. At the end of the TV Series, he is seen to be recovering from comatose state after incidentally absorbed Mr Gentleman's information during the execution of Operation Sleeping Books.

Read Or Die OVA:

Yomiko's boss, the acting head of the Special Operations Division. Joker is a stereotypical Englishman (Kurata describes him as "someone whose photo you would expect to see in the entry for 'Englishman' in the Encyclopedia Britannica"); his cool head and skill with words are his primary weapons. He is extremely cool and clever in the novel most of the time because of his ambition to become the actual head of the Division and gaining control of the whole country only under the command of Gentleman. Later in the novel, Joker's main thought is to destroy Gentlemen after he gained full control of the British Empire including all military, police, military intelligence and such which Gentleman appointed him for 9 days.

(Source: Wikipedia)