Marvolo Gaunt

"He...was left in squalor and poverty, with a very nasty temper, a fantastic amount of arrogance and pride, and a couple of family heirlooms that he treasured just as much as his son, and rather more than his daughter."

- Albus Dumbledore on Marvolo Gaunt

Marvolo Gaunt was a pure-blood wizard and descendant of Salazar Slytherin. He was the grandfather of Tom Marvolo Riddle, later known as Lord Voldemort, through his daughter Merope. Marvolo died soon after being released from Azkaban, where he was briefly imprisoned for assaulting Ministry personnel.

Family Life
"Salazar Slytherin's! We're his last living descendants, what do you say to that, eh? Don't you go talking to us as if we're dirt on your shoes! Generations of purebloods, wizards all — more than you can say, I don't doubt!"

- Marvolo to Bob Ogden

Marvolo, his son Morfin, and his daughter Merope were the last of the Gaunt family, descendants of Salazar Slytherin. Generations of inbreeding caused a vein of instability and violence to flourish in the family. This lack of sense coupled with a great liking for grandeur meant that the family gold was squandered several generations before Marvolo was born. As such, he and his children lived in poverty in a ruined cottage near Little Hangleton.

Marvolo's relationship with his children was terrible. He seemed to tolerate and maintain a tenuous relationship with his son Morfin, who was furiously loyal to Marvolo and his family's ideals, while just as unstable and violent. On the other hand, Marvolo genuinely despised his daughter Merope, whom he derided as being a Squib and expected to do all the cooking and cleaning. He and Morfin were both emotionally and physically abusive towards Merope, to the point of almost strangling her. Marvolo also conversed with his children in Parseltongue.

Imprisonment
Morfin, being mentally deranged and having little regard for secrecy, frequently using magic in front of, and upon, Muggles, with his father approving of his actions. This inevitably brought him into conflict with the Ministry of Magic. When the Head of the Magical Law Enforcement Squad, Bob Ogden, visited the Gaunts to address the issue, they resisted violently, with Marvolo justifying Morfin's actions and resistant to Ogden's calm attempts at discussion. Just as Ogden rose to leave, Morfin revealed that Merope had a romantic admiration for the Muggle he attacked: Tom Riddle Sr. Marvolo, losing all control, attacked his "filthy little blood traitor" of a daughter, though Ogden stopped him from strangling her by using a Relashio jinx.

Morfin in turn defended his father from further attacks by firing a storm of jinxes towards Ogden, leading him to run for his life. Ogden Apparated back to the Ministry and returned with reinforcements within fifteen minutes. Marvolo and Morfin attempted to fight, though were both overpowered and removed from the cottage. Both men were brought before the Wizengamot and sent to Azkaban, with Morfin receiving a three-year sentence, and Marvolo, because he injured several Ministry personnel, received six months.

Death
Merope, once Marvolo and Morfin were safely in prison, found herself alone and free for the first time in her life, and her magical abilities, which were suppressed by years of torment from her father and brother, flourished. She took the opportunity to escape from the desperate life she had led. Likely using a love potion, Merope seduced and married Tom Riddle Sr..

After his time in prison, Marvolo returned to the cottage, arrogantly and foolishly expecting Merope to have dutifully awaited his return and be waiting with a hot meal ready on his table. Instead, he found the shack empty and abandoned, a clear inch of dust covering the inside. He also found Merope's note of farewell explaining what she had done.

Marvolo's shock was so great that he never mentioned her name or existence from that time forth. The shock of Merope's "desertion" was so great that it led to his early death. Other factors included him being greatly weakened by his time in prison, and he possibly never learned to feed himself. Marvolo did not live to see Morfin return to the cottage.

Etymology

 * The name Marvolo may be derived from Malvolio, which loosely translates into "ill will" in Latin. It is also the name of a character from William Shakespeare's Twelfth Night. Malvolio is a Puritan who despises all kinds of fun and games, perhaps alluding to Marvolo's extreme prejudice and cruelty.
 * The word gaunt is defined as "haggard, drawn and emaciated" and "bleak, desolate".