Lord Voldemort grew up as Tom Riddle. He went to Hogwarts and had great potential. Little did any one know he was growing up to be the greatest Drak wizard of all time. Dark spread over the magical realm and Lord Voldermort took over, with awful consequenses. He was so feared even now no one can even speak his name.
One night, Lord Voldemort killed Harry's parents, and tried to kill Harry. But when he did, he was killed and Harry was okay. Everyone was overjoyed. He has since, and will for long times to come, tried to regain power. Since he is not fully human, can never die.
Lucius Malfoy was part of Lord Voldemort's inner circle when he was in power. He is Draco's Father. Once Voldermort was gone, he said he was a kind of "hypnotized" of sorts and the real him was not part of that. Most think otherwise, and they're right.
He set up an elaborate scheme in Harry's second year to have all muggle borns (and Harry and Ginny) killed. It didn't work, and Lucius lost his job, and his house elf, Dobby.
Professor Quirrell was kind of a joke when he was a teacher at Hogwarts. Everyone bought his pitiful, studdering act. There were rumors he'd been through a lot with monsters and vampires,and that's why he was so scared and studdered. They thought the turban he wore held garlic in it so he could be safe from vampires at all times. It was all just an act so they would never suspect him.
He was a servant of Voldemort, and inside his turban, on the back of his head, was the remains of Lord Voldemort. His face was in the back of Quirrell's head! When Harry met up with him and battled him, Quirrell was burned because the touch of something as good as Harry was that hurtful to him. When Dumbledor got there just as Harry was getting badly hurt, he saved Harry and Quirrell was dead.