Sebastian Michaelis (セバスチャン・ミカエリス Sebasuchan Mikaerisu) is the very attractive butler of the Phantomhive household and acts as Ciel's bodyguard. Sebastian's appearance is similar to that of Ciel's father. Sebastian often describes himself through the phrase "I am nothing more than a butler." (私はあくまで執事ですから Watashi wa akuma de shitsuji desu kara). The phrase plays on the word "demon" (あくま akuma) and the phrase "to the end" (あくまで aku made). It can also translate to "I am a demon and a butler". In Funimation's English translation, this phrase becomes "I am one hell of a butler," which is, obviously, another play on his demonic origins.
Being a butler and a bodyguard are two jobs he is completely devoted to. He follows Ciel's orders faithfully, however, he is not overly concerned about Ciel's well-being as he insults and even harms Ciel to see his reaction. He calls Ciel a "brat" who treats his workers rudely. Sebastian is also shown to be a bit obsessed with cats, in chapter 44 of the manga, he is shown to be hiding 15 cats in his room. He also seems to love a stray black cat with amber eyes, though it has yet to make another appearance. Comically the only times he does not follow Ciel's orders is when he sees a cat, too dazed observing it to pay any attention to anything else.
He is highly skilled in any area, and handles every task, no matter how impossible it is, as well as any problem that arises from the errors of the other staff with ease, stating it is only natural as the butler to the Phantomhive family. This is due to the fact he is a demon bound by a Faustian contract to abide by Ciel's will. A sign similar to the one marking Ciel's right eye can be found on Sebastian's left hand, which has been used on one occasion to twist the arm of a kidnapper without touching him. The name Sebastian is in fact a temporary name given to him by Ciel and was previously held by Ciel's dog. It has been established that he is a cat-person, ignoring Ciel's words to comfort a stray cat. In turn, he shows high disdain for dogs, especially towards Pluto. In the anime adaption, Sebastian can take the form of a crow or a cat. Sebastian's true demonic form has not been fully revealed. However, a depiction of sharper teeth, high-heeled boots, and elongated nails have been given. In the anime, his true form is also shown, but only briefly in glimpses at the finale, sporting high-heel boots and claw-like hands (the appearance of a goatee is given, but was subsequently discovered to be a animation error). In the manga adaptation, Sebastian appears to Ciel to form the contract in his true form, while in the anime version, he appears as a crow. He is voiced by Toshiyuki Morikawa on the first drama CD, Daisuke Ono in the anime adaption and on the second drama CD, and J. Michael Tatum in the English dub.. His name is similar to that of FatherSebastien Michaelis, who compiled a hierarchy of demons in Hell.
In The Second TV Series, Sebastian resurrects Ciel with his Family Ring (which was somehow located in a "New Moon Drop" tea box under Alois Trancy's manor). He comes into Trancy's manor in the disguise of a wanderer needing to shelter himself from a storm, however, criticizes Claude Faustus's abilities as a butler saying he does not seem to take his responsibilities seriously when he sees a drop of sauce on the side of his dinner plate. This alerts Claude that he is Sebastian as he later on attacks him when he gets the "New Moon Drop" Tea box from Alois. In the battle, the large traveler's trunk he is carrying opens revealing Ciel's lifeless body and when Alois gets excited and seems to know Ciel and wants to touch him, he says that he cannot allow such a low person as Alois and his copy-cat Claude catch them. Sebastian resurrects Ciel and follows his orders obediently as before, however, he does not mention the Trancy incident nor tell Ciel anything that has happened (It seems Ciel has forgotten a lot of things that had transpired in the first TV series). The air around the relationship between Ciel, Sebastian, Alois, and Claude is an enigma that seems to be one of the pinnacles of the second series.
It is later revealed that when Sebastian had wanted to consume Ciel's soul, Claude had come (in the form of a spider) delivering a venomous bite that killed Ciel prior to having Sebastian consume him - thus voiding their contract.§ Claude then merely tells Sebastian that he was acting upon the orders of Alois Trancy who wanted to obtain Ciel. As Ciel has forgotten the revelations at the end of Season One, his soul is incomplete. Sebastian and Claude then forge a contact with their blood upon a rose (which turns black) that Claude will only come after Ciel when Ciel's revenge is complete and Sebastian agrees that Alois Trancy will be the target of Ciel's revenge. But the progress of this contract has gone haywire. Claude (in episode eight) kills Jim McCain aka Alois Trancy because Jim has expressed love for him - this makes Claude no longer wish to consume Alois' soul. Instead, he hypnotizes Ciel and puts the Trancy ring upon him (which contains Jim's soul) and makes him believe that Sebastian had killed his parents (As Alois and Ciel share similarities with their memories being mixed). Sebastian becomes helpless when Ciel, using his contractual seal, tells him to disappear from his sight as he now recognizes Claude as his only butler and that Sebastian was responsible for the deaths of his parents and the burning of the Phantomhive household.
Sebastian complies only to go away to a distance and mutters that though he was late in preparing dinner, it will be served - implying that he will defeat his enemies. His form becomes glowering black and eyes pure red, for there are no longer any 'contractual handcuffs' to obey and claims that he will, "Clean up every last spider."