While in human form, it appears as a female human with shoulder length light brown hair and pale skin. It wears a grey suit blazer over a knee-length pencil dress, along with dark stockings, black pumps and red-tinted glasses.
In the second stage of transformation, it appears as a succubus with red skin, enlarged pale eyes, tattered wings, clothes and messy hair. It also has markings on its skin, fangs, goats' feet and horns.
The Boss appears only during the eponimously titled episode "The Boss". It is the head of the Public Resources department at a magazine distributing company where Dan and Chris briefly work as temps, calling the company's debtors and late fee holders and persuade them to pay their debts.
It initially hates Dan and picks on him due to his hatred of work but as soon as it discovers his talent for angrily threatening people into paying their debts, it takes a liking to him. The Boss is quick to promote Dan and takes him on as its apprentice, giving him his own office and a large pay raise.
However, both Dan and Chris soon discover that it is an otherworldly demon set on causing as much harm to people as possible. Dan is initially impressed by this and considers joining its legion. However, when it demands that Chris be killed because he knows too much, Dan turns on it and attacks it with holy water in her office. The amount Dan threw on her was not enough to kill it and it morphs into a giant beast before trying to kill Dan and Chris. Chris distracts him while Dan prepares more holy water and later uses it to drive it back to the depths of hell through the dimensional hole it opened in its office. As it falls down the pit of hell, it swears it will get its revenge on Dan.
So far, they make no further appearences after Dan casts it back into (what is pressumed to be) hell.