Who could replace Yahya Sinwar as Hamas's leader?

Yahya Sinwar's death has raised many questions about the future of the war in Gaza, perhaps none more pressing than who will replace him as Hamas's leader.

The Israel Defense Forces said Thursday that the mastermind behind the Oct. 7 attack on Israel had been killed in a routine operation in the southern Gaza Strip.

Sinwar was seen as an intransigent figure in efforts to broker a cease-fire and hostage release deal between Israel and Hamas, and his death has spurred cautious optimism about negotiations restarting.

But whether Hamas or Israel will become more willing to agree to a truce may depend largely on who steps into Sinwar's shoes. These are some of the leading candidates to replace him..

Mahmoud al-Zahar

Mahmoud al-Zahar is a founder and senior member of Hamas, considered to be "hawkish" and "socially conservative" even by the standards of the militant group, according to the European Council on Foreign Relations.

He was elected to the Palestinian Legislative Council (PLC) in 2006 and was appointed as the group's first foreign minister after Hamas's electoral win that year. He reportedly survived assassination attempts by Israel in 1992 and 2003.

Reuters reports that he has made no public statement or appearance since Oct. 7.

Al-Zahar previously worked as a doctor in Gaza and established medical charities.

Mohammed Sinwar

One potential successor could be Yahya's brother, Mohammed Sinwar. His ascension would likely signal a continuation of his brother's approach to cease-fire talks.

A U.S. official told CNN that if Mohammed were chosen "negotiations are totally screwed," and a former official described him as being "cut from the same cloth" as his brother.

Mousa Abu Marzouk

Mousa Abu Marzourk helped create a branch of the Palestinian Muslim Brotherhood that later formed Hamas, according to the European Council on Foreign Relations. He remains a member of its top political bureau.

In the '90s, as the head of Hamas's political bureau, Israel charged him with funding and helping organize terrorist attacks, The New York Times reported.

He agreed to give up permanent resident status in the U.S. and not contest terrorism accusations after spending nearly two years in a jail in Manhattan in the 1990s. The U.S. then deported him to Jordan.

Mohammed Deif

It's unclear if Mohammed Deif is alive. Israel's military had said Deif was killed in an airstrike earlier this year, but a top Hamas official told The Associated Press in August that he's still alive.

A founding member and commander of Hamas‘s military wing Izz al-Din al-Qassam Brigades since 2002, Deif was believed to be a mastermind of the Oct. 7 attack alongside Sinwar, Reuters reported.

A former counterterrorism adviser to the U.S. State Department described Deif as a "particularly hard-line Hamas official" with close ties to top commanders, per a BBC report in 2021.

Deif is also credited with designing one of Hamas's main weapons, the Qassam rocket, and the network of tunnels beneath Gaza, according to the BBC .

Khalil al-Hayya

Khalil al-Hayya is a member of Hamas’s Qatar-based political bureau and has been the lead negotiator in cease-fire discussions in Doha. He currently lives in Qatar.

The U.S. official told CNN that al-Hayya is "probably who the U.S. would want" due to his established role in cease-fire talks. He was a main figure in negotiating a cease-fire deal with Israel during the 2014 Gaza war, according to the European Council on Foreign Relations.

The Associated Press reported in August that al-Hayya was also seen as a potential successor to Hamas's former political chief, Ismail Haniyeh, who was killed earlier this year. That role went to Sinwar.

Al-Hayya said in April that Hamas would lay down its weapons, convert into a political party and agree to a truce of five years if an independent Palestinian state is established along pre-1967 borders, per The Associated Press.

The Hamas leader survived an airstrike on his home in Gaza in 2007, which killed members of his family.

Khaled Mashal

Khaled Mashal was the overall Hamas leader for more than a decade starting in 2006, as well as the former leader of its political bureau.

However, he would be an unlikely choice given his support for a past uprising against Syrian President Bashar al-Assad, which caused a rift with patron Iran, according to CNN.

Mashal survived an assassination attempt against him in the late 90s.

Reuters interviewed the exiled Hamas leader in Qatar, where he lived, earlier this month.

"Palestinian history is made of cycles," the 68-year-old said. "We go through phases where we lose martyrs and we lose part of our military capabilities, but then the Palestinian spirit rises again, like the phoenix, thanks to God."