Severus Snape

Appearance:
Snape was described as a thin man with pale skin, a hooked nose, and greasy shoulder-length hair. His black eyes were cold and empty, reminiscent of "dark tunnels." He spoke in a soft, low voice with a hint of steel. He preferred to wear black, billowing robes, which gave him the appearance of a bat.
Snape was unsociable, abrupt, strict with students (except Slytherin), picking on them at the slightest provocation, especially Gryffindors and Harry Potter in particular. He was extremely unkempt and never washed his hair.
Magical abilities:
a brilliant potion maker;
he was a master of occlumency (concealing thoughts and feelings) and legillimency (reading thoughts);
a skilled duelist;
He invented several unique spells, including Sectumsempra (inflicts sharp, bloody cuts), Levicorpus (lifts the victim upside down), Muffliato (fills the ears with a humming sound), and others.
Position and role at Hogwarts:
Potions teacher (1981–1996);
Defence Against the Dark Arts teacher (1996–1997);
Dean of Slytherin House (1981–1997).
Facts:

• Doesn't really like Muggles, not at all;
• He is a member of both the Death Eaters and the Order of the Phoenix.