The Gentlemen: - Four white skinned floating demons that require human hearts in order to survive. The Gentlemen came to Sunnydale along with their crazed footmen to reap the seven hearts that they needed. In order to do this they first steal the voices of al the humans in town, causing a wide spread panic and rumours of a town wide laryngitis outbreak. They then set about harvesting the hearts that they needed. They only known way to stop them is to scream, and with no voice this is hard to do. Of course, they hadn't counted on the Slayer and Buffy first finds their lair, then her voice and, letting out a piercing scream causes all their heads to explode.
Gnarl: When Willow returns t Sunnydale after her recuperation in England, she is so scared of rejection that she unknowingly causes herself to become invisible. Her vulnerability and aloneness attracts the demon Gnarl, who is living in a cage. Gnarl feeds on human skin which he obtains by paralising his victims with one of his long claws and then stripping of their skin piece by piece. Luckily Buffy finds Gnarl and Willow in time and kills the demon before he can do too much damage.
Ubervamp: The vampires that vampires fear, ancient and ferocious the Ubervamps are summoned by The First who creates an army of them to use in it's battle against the Slayer. Strong and very hard to kill, a normal stake just not getting it done, they still perish from decapitation and exposure to direct sunlight. In the final battle, Spike destroys them all using the amulet given to Angel by Wolfram & Hart, it's power causing bright rays of sunlight to course through the Hellmouth itself, destroying Sunnydale in the process.