Known only by his profession, the Undertaker is a mysterious man whose scarred face is never fully visible beneath his long hair and crooked top hat. He occasionally provides information to Ciel. While he finds Ciel amusing and enjoys helping him out, he has nothing but disdain for the Queen. He tends to punctuate his words with sweeping gestures and creepy giggles and seems to spend a good deal of time inside of coffins. He also likes to hear jokes and ask people to tell him for exchanging information.
In the anime:
In the Manga:
(Source: Devil's Food Cake Site, Wikipedia)