Harry's courageous godfather Sirius Black was one of the last family members he had. Loyal to the end however he helped Harry wherever he could and died protecting him in the battle at the department of Mysteries. Although he's not truly dead if he's immortalized as a 9.5cm POP-figure!

Backstory:

Sirius Black, also known as Padfoot or Snuffles (in his Animagus form) was a pure-blood wizard, the older son of Orion and Walburga Black, and the brother of Regulus Black. Although he was the heir of the House of Black, Sirius disagreed with his family's belief in blood purity and defied tradition when he was Sorted into Gryffindor instead of Slytherin at Hogwarts School of Witchcraft and Wizardry, which he attended from 1971-1978. As the rest of his family had been in Slytherin, he was the odd one out.

As Sirius's relationship with his relatives deteriorated, he gained lifelong friendship in James Potter and Remus Lupin. Peter Pettigrew was a friend as well for ten years. The four friends, also known as the Marauders, joined the Order of the Phoenix to fight against Lord Voldemort and his Death Eaters during the First Wizarding War. Sirius was named the godfather of Harry James Potter, the only son of James and Lily Potter. When Pettigrew betrayed the Potters to Voldemort, Sirius sought to exact revenge on Pettigrew. However, Pettigrew was able to frame Sirius for his betrayal of the Potters, the murder of twelve Muggles, and the staged murder of Pettigrew before Sirius could accomplish this.

He was sent to Azkaban for 12 years, but eventually managed to escape and expose the truth to Harry. Although the rest of the world considered him a criminal until sometime after his death at the hands of cousin: Bellatrix Lestrange.