Sebastian takes on the appearance of a tall, handsome adult with black hair, reddish brown eyes, pale skin, and black fingernails. The back of his left hand contains the mark of his Faustian contract with Ciel Phantomhive. Sebastian typically dresses in a butler's outfit, which consists of black trousers, a six-buttoned double-breasted tailcoat, and a gray vest; on is his shirt cuffs and tie is the Phantomhive crest. He also sports white gloves, a pocket watch, and a chained silver lapel pin bearing the Phantomhive crest, which is traditionally worn by the house's head butler. Details of Sebastian's demonic form include high-heeled stiletto boots, sharp claws, glowing fuchsia irises, slit pupils, and longer, sharper teeth, with dark wings and multiple eyes. Sebastian is devoted to Ciel Phantomhive. He faithfully carries out every one of Ciel's orders while ensuring that the Phantomhive household runs smoothly as the head butler. He does not sleep—demons deem sleep a luxury—and often spends his nights fulfilling his duties. He is sometimes critical of his master and how he treats his workers, but once admitted that he is not averse to the butler lifestyle despite the concomitant daily troubles. One of his quirks is that he always responds to Ciel's orders with the saying "Yes, my lord (御意イエス ご主人様マイロード )." Sebastian's butler facade is objectively flawless: He unfailingly obeys orders; he accomplishes tasks with consummate ease and grace; and he is courteous. Nevertheless, Sebastian is in actuality a cold and calculating demon; he is relentless when attacking others on Ciel's orders, and he occasionally puts Ciel in nonfatal danger for the sake of his own amusement. He usually behaves in a cavalier fashion when Ciel appears to be in danger, as he is confident in his ability to rescue him, but he may express concern when the situation grows precarious, such as when Angelina Dalles or Undertaker posed a considerable threat to Ciel's life. Sebastian is cunning and morally bankrupt, and he has no qualms about lying, cheating, and seducing others to gain the upper hand. He strictly adheres to his demon aesthetics and principles, one of which is not entering into multiple contracts, for he views such as inelegant. His paramount goal is to claim Ciel's soul. Sebastian is fascinated with humans and how seemingly insatiable they are, for they are willing to "drag others down to get what they want, even in death." In general, he regards them as "difficult creatures." Additionally, he has a great and mutual distaste for Grim Reapers. Sebastian views money as "rubbish" and "materialistic." He is fluent in French and Latin, enough to teach the latter. He is also proficient in Deutsch (German) and East Franconian, a dialect in Southern Germany. Moreover, he profoundly adores cats and once kept at least thirteen hidden in his wardrobe to prevent Ciel from finding out.

Finnan is a 16-17 year old boy with green eyes, blonde short hair, and pale skin. He is the Manor's gardener. Finnian was an experiment, and because of that, he has superhuman strength. Ciel gave his name "Finnian", he's actually known by S-012. He's sweet, kind, and loves working for Ciel.

Mey-Rin is the maid of the manor. She has red hair with two short pigtails. She has glasses but she can't really see without them. She's pale and her outfit is an usual maid attire. She's kind, sweet, and also protective of Ciel. She can be awkward and break things but she doesn't mean harm. She also know how to shoot guns.

Baldroy is the Manor's chef. He has short blonde hair, pale skin, and green eyes. He usually wears anything but sometimes he wears a white long sleeve shirt. He used to be in the war, and also watched his family die: his wife and son, in a burning fire. He's brave, kind, and can't really cook well. He gets yelled at Sebastian because of it.

Tanaka is the main butler of the Manor. He's old with grey slick back hair and a grey mustache. He has been the butler for the Phantomhive manor since Vincent and Rachel Dallas Phantomhive. Same as Sebastian, he has the same attire.

Snake has white short fluffy-ish hair, with scales on his face and pale skin. He also has green eyes. He is the footman of the Manor and communicate through his snakes: Emily, Wordsworth, Goethe, Oscar, Wilde, Webster, Brontē, Donne, and Keats.

Grelle Sutcliff is a transgender (Male to Female) grim reaper with long red hair that goes to her butt, chartreuse phosphorescent (neon yellowish-green) eyes and suffer from severe nearsightedness so Grelle has red glasses. Grelle wears a distinct crimson-and-black Grim Reaper ensemble featuring a signature's of red u coat, a vest, and high heels. Grim Reapers can kill a demon instantly but Grelle obsesses over Sebastian or any "hot" guys.