Lucius Malfoy

Lucius Malfoy is a Death Eater and head of a pure-blood Wizarding family; he lives with his wife Narcissa Malfoy (née Black) and their son Draco at the Malfoy Manor in Wiltshire. Lucius is a school governor of Hogwarts before he is sacked and has very close connections at the Ministry of Magic. To maintain his reputation and influence, he makes donations to the Ministry, to charity, and to St Mungo's Hospital. He was educated at Hogwarts, where he was a prefect in Slytherin House.
Just before Draco and Harry's second year at Hogwarts, Lucius plants Tom Riddle's diary in Ginny Weasley's potions cauldron while she is shopping for school supplies at Flourish & Blotts, in a plot to use her to reopen the Chamber of Secrets, which would lead to attacks on Muggle-born students. Lucius knows the diary is cleverly enchanted, but is not aware that it contained a part of Voldemort's soul. Lucius intends to use the opening of the Chamber of Secrets by Ginny to discredit her father, Arthur Weasley, and Dumbledore. Lucius's plans are ultimately thwarted with the help of the Malfoys' house-elf Dobby, and Harry, but not before the Chamber is opened and Lucius uses the ensuing terror (and threats to attack their families) to influence the school's Board of Governors to discredit and dismiss Dumbledore as Headmaster. Subsequently, Harry tricks Lucius into setting Dobby free. Upon this, Lucius attempts to attack Harry with his wand but Dobby disarms him before he can do any harm. Lucius is ultimately stripped of his title as a Hogwarts school governor. Despite his sacking, he still maintains strong ties with the Ministry of Magic.
Lucius next appears in the beginning of Harry Potter and the Goblet of Fire during the Quidditch World Cup, sharing prime seats in the Top Box with Minister of Magic Cornelius Fudge. Later in that book, when Voldemort rises again and summons his Death Eaters, Malfoy rejoins him, claiming that he had done everything he could all along to find Voldemort and help him rise again (though Voldemort knows he is lying). Harry, who witnesses Malfoy's declaration of loyalty to Voldemort, tells Minister Fudge, who refuses to believe him, and the wealthy Malfoy maintains strong ties with the Ministry. During the climax of Harry Potter and the Order of the Phoenix, Malfoy is the leader of the Death Eaters who are to retrieve the prophecy from Harry in the Hall of Prophecy. Lucius tries several ways to get the prophecy from Harry without breaking it, but the boy and his friends manage to escape from the Hall. Malfoy finally meets him in the Death Chamber, where Harry is about to give it to Malfoy when the Order of the Phoenix breaks into the Ministry and begins to duel the Death Eaters. Dumbledore himself arrives at the end of the battle and Malfoy is captured and sent to Azkaban.
By the final book, Voldemort has given Malfoy his freedom, though he looks significantly the worse for wear. Voldemort treats him with great contempt, has hijacked his house for Headquarters, and is forcing his son to do dark deeds against his nature, sparking sympathy for the notorious family for the first time in the series. Later in the book, Lucius, along with his wife and sister-in-law, accidentally allow Harry and his friends to escape from Malfoy Manor. Voldemort punishes them severely, eventually putting them under house arrest. Despite his long-standing position as a Death Eater and Voldemort's advocate of pure-blood supremacy, Lucius has decided his love for his family is more important than his involvement in the war. During the Battle of Hogwarts, he pleads with Voldemort to let him onto the battlefield to locate his son. He and the rest of his family are reunited at the end of the book. Following Voldemort's death, Lucius, Narcissa and Draco all manage to "weasel their way out" of being sent to Azkaban due to Narcissa's aiding Harry in the Forbidden Forest.