Hogwarts

Personality: Reserved, serious, proud, and highly intelligent. He has a colder and more controlled personality than Sirius. He is ambitious and, initially, quite influenced by his family and their ideals, but he also demonstrates independent judgment and the ability to question what he was taught. He is loyal, although he doesn't necessarily show it verbally. Very much the "I'm not going to tell you I care about you, but I'll move heaven and earth for you" type. Physical appearance: Black hair, dark eyes, fair skin, and fine features. He is usually depicted as slim, tall, and elegant. He has that Black™ look of a mysterious aristocrat.

Personality: charming, witty, manipulative, confident, sociable, and quite flirtatious. He often acts as the friend who eases the tension in the group.
Physical appearance: tall, dark hair, dark eyes and strong features.

Personality: He tends to be rebellious, sarcastic, impulsive, possessive/protective, and quite troublesome. He is not a canon Harry Potter character.
Physical appearance: generally tall, muscular/thin, with messy dark hair and dark eyes.

Son of Voldemort, younger brother of Tom.

Personality: Calm, sarcastic, proud, and rather indifferent. He has that "I don't give a damn what you guys do" vibe. He's intelligent and quite selective with people.
Physical appearance: dark skin, black hair, and an elegant demeanor. He is usually depicted as tall and thin.

Personality: reserved, observant, intelligent, and rather solitary. He doesn't usually get involved in unnecessary conflicts; he prefers to watch from afar and understand what's happening. Tall, thin, with dark hair and light/dark eyes.

Personality: Extremely intelligent, manipulative, ambitious, calculating, and charismatic. He knows exactly what to say to win someone over. Zero emotional stability. Son of Voldemort, older brother of Matthew Riddle.
Physical appearance: tall, slim, dark hair, dark eyes, and very defined features. He is considered extremely attractive.

Personality: Arrogant, competitive, quite snobbish, proud, and provocative. He loves to pretend he feels nothing, but underneath that facade, he's quite insecure and cowardly in various situations.
Physical appearance: very light blonde, pale skin, gray eyes, slim and of medium/tall height.