He has black, short hair and wears glasses similar to those worn by William Spears, a character from the previous Kuroshitsuji series. He has yellow, slanted eyes and a somewhat angular facial structure. His chin is quite flat. Like Sebastian, Claude is able to transform his body. In the first episode he is seen in the form of a spider before making the contract with Alois. He and Sebastian appear to be similar in height.
He wears an outfit similar to the one Sebastian Michaelis wears.
It has been shown that, like Sebastian, the mark of the Faustian contract with Alois is on his left hand covered by the glove he wears.
He has a very different personality from Sebastian Michaelis, in that he speaks and acts emotionlessly, not even responding to direct taunts such as Alois undoing his buttons moments after Claude fixed them. He seems to know Sebastian well, although within moments of seeing each other they begin to fight. Claude is loyal to his master, and wants to, as he says "devour [him].". Claude obeys all his master's orders, but makes miniscule mistakes on occasion, such as allowing a drop of sauce to "dirty" an otherwise perfect dinner plate.
He is shown to know Sebastian very well, and hate him.