Sons of Fëanor

The Sons of Feanor were the seven Noldorin Elves. Six out of the seven sons die in the Silmarillion.

The seven Sons of Fëanor, alongside their father, swore an Oath to recover the stolen Silmarils. This Oath required Fëanor and his kin to seek with vengeance anyone who withheld a Silmaril from them. The seven sons followed Fëanor into his exile from Valinor and into Beleriand, where they fought many battles to reclaim the precious gems of their father. The Oath led them to participate in three different Kinslayings. Six out of the seven sons died as a result of the Oath, either in battle or, in Maedhros' case, by suicide. Maglor was the only Son of Fëanor to survive the war, though his final fate is unknown.

He sacrificed his high Kingship when he jumped into the fiery chasm while holding the Silmaril in an attempt to rescue Fingon, the son of Fingolfin. [1]

Maglor ruled over the Maglor’s Gap. After the death of Maedhros, Maglor went away to the sea and dumped his Silmaril into the ocean. He was never seen again.

All three of them died when the Son of Feanor waged a war on the Elvish kingdom of Doriath.

These twins were the youngest sons of Feanor. They were known as the hunters in Middle-Earth.
They died when they attacked the elves at the Mouth of Sirion because the Silmaril from Doriath was hidden there.

1. ^Why did Maedhros commit Suicide? - Sci-Fi Stack Exchange.