Police officer Ron Gvili was one of 251 hostages seized and taken to the enclave by Palestinian Hamas militants during their October 7, 2023 cross-border attack that triggered the war.
At the time of a ceasefire deal that Israel and Hamas agreed in October, 48 hostages remained in the Gaza Strip, 28 of whom were believed to be dead, including Gvili.
Handing over all remaining living and dead hostages was a core commitment written into the first phase of the ceasefire deal.
Subsequent stages remain to be fulfilled, with deep splits over what comes next, including Hamas disarmament.
In a statement, the International Committee of the Red Cross said it had facilitated the return of 15 deceased Palestinians to the Gaza Strip after Israel recovered Gvili's remains.
"This marks the completion of a months-long operation that reunited families and supported the implementation of the ceasefire agreement," the ICRC statement added.
The operation began in October with the release of 20 living hostages by Hamas and 1808 Palestinian prisoners by Israel, the ICRC said.
In subsequent phases, the ICRC smoothed returns of the deceased, including 27 of 28 hostages and 360 Palestinians.
"We are relieved to have helped reunite families with their loved ones. For families whose deceased relatives were returned, we hope this brought the possibility to fully mourn," said Julien Lerisson, the ICRC's regional head.
The Hamas-run health ministry confirmed it had received the 15 bodies, saying it would now try to identify them.
Only 99 of the Palestinian bodies handed over since October have been identified, it added, with health officials forced to bury unidentified bodies in mass graves.
In the latest violence rattling the fragile ceasefire, medics said two men were killed by Israeli forces in eastern Khan Younis, in an area adjacent to where the army operates.
The Israeli military told Reuters it was unaware of any casualties as a result of Israeli fire on Thursday.
The Gazan health ministry said Israeli air strikes, tank shelling and gunfire have killed at least 490 people since the truce took effect in October after two years of war that widely demolished the Palestinian enclave.
Later in the day, an Israeli air strike killed at least one Palestinian and wounded others in the Maghazi camp of the central part of the Gaza Strip.
It was unclear what prompted the attack, and the Israeli military did not immediately respond to a request for comment.
Israel said four soldiers have been killed by Palestinian militants in the small coastal territory during the ceasefire.
The two sides have traded blame over the truce violations.
By advancing to phase two, the US and mediator partners Egypt and Qatar must confront the more contentious issue of Hamas disarmament, which the group has rejected.
The plan also calls for deploying an international peacekeeping force.
