Dror Or, a 49-year-old held captive in Gaza, has died, the Hostages Families Forum said on Friday.
Mr Or marks the 38th hostage killed, the forum said.
He was one of about 250 people abducted when Hamas attacked southern Israel on October 7th, killing around 1,200 people, mostly civilians.
Israel says militants still hold around 100 hostages and the remains of more than 30 others.
Dozens of people demonstrated on Thursday night outside Israel’s military headquarters in Tel Aviv, demanding a deal to release the hostages.
Meanwhile, Hamas said it would send a delegation to Cairo as soon as possible to keep working on ceasefire talks.
A leaked truce proposal hints at compromises by both sides after months of talks languishing in a stalemate.
The Israel-Hamas war has driven around 80 per cent of Gaza’s population of 2.3 million from their homes, caused vast destruction in several towns and cities, and pushed northern Gaza to the brink of famine.
The death toll in Gaza has soared to more than 34,500 people, according to local health officials, and the territory’s entire population has been driven into a humanitarian catastrophe.
