Name: Claude Faustus
Age: Unknown
Birthdate: Unknown
Hair: Black
Eye color: Gold
Height: 191 cm (6'3")
Race: Demon

The butler of the Trancy household.

He is a demon and he has a line similar to that of Sebastian's, which is "私は旦那様を飽くまで貪りたい" (Watashi wa danna-sama wo akumade musaboritai) which means "I want to greedily devour you to the end, my master." The kanji of "akumade" might mean something else.

Claude has a different personality than that of Sebastian Michaelis in which he speaks and acts motionlessly, not even responding to direct taunts from Alois, such as him undoing his buttons moments after Claude fixed them. He seems to know Sebastian well, but within moments of seeing each other they begin to fight.

This is probably due to the fact that Claude seems to hate Sebastian.
He is very loyal to his master and knows his master's darkness.

He has black, short hair and wears glasses similar to those worn by William T. Spears. He has yellow, slanted eyes and a somewhat angular facial structure. His chin is quite flat. Claude can transform his body like Sebastian.

In the first episode he is seen in the form of a spider before making the contract with Alois.

He wears an outfit that is similar to the one Sebastian wears, but Sebastian wears a tie while Claude wears a ribbon, and Claude had one button of his tailcoat on whilst Sebastian does not.

Like Sebastian, his contract mark with Alois is one his left hand covered by the gloves he wears. However, his mark isn't always visible, only becoming so when he nears Alois.

In episode 4, it is shown that his tongue is incredibly long, reaching to the upper of his nose at rate.
Claude says "Yes, your Highness" when following Alois' commands, whereas Sebastian says "Yes, my Lord."

(Source: Kuroshitsuji Wikia)