The former head of the Palestinian Islamic Jihad movement died Saturday night at the age of 62 after a long illness.
Ramadan Shalah had been in a coma for more than three years after heart surgery, the group said. It didn't say where he died, but he is believed to have been in Lebanon.
Although the Gaza Strip born was affiliated with the Muslim Brotherhood movement in his youth, he was among the Islamic Jihad's founders, almost a decade prior to Hamas.
Shalah did not stand out over the years as a particularly charismatic leader in the Islamic Jihad, but managed to maintain his status while the organization's military arm strengthened through long-term funding from Iran.
Shalah led the Iranian-backed group for over 20 years, after its founder, Fathi Shikaki, was shot dead in Malta in an attack widely attributed to Israel. In 2018, the group named Shalah's deputy, Ziad al-Nakhalah, as the new leader.
Nakhalah is more extreme and impulsive than his predecessor and has prompted frequent military confrontations between Israel and the organization.
Palestinian Islamic Jihad has offices in Syria and Lebanon, but most of its activities are focused in the Gaza Strip. Mosque loudspeakers across Gaza blared in the evening with tributes to Shalah.
Last year, the movement took part in several rounds of heavy fighting with Israel. But in recent months it has remained committed to an unofficial truce brokered by regional mediators between Israel and Hamas, the larger Islamic group ruling Gaza.
Palestinian Islamic Jihad previously has taken part in numerous suicide bombings, shootings and rocket attacks that killed dozens of Israelis.
Shalah was on the U.S. "most wanted list" of terrorist suspects with a $5 million reward for information leading to his arrest or conviction.
Elior Levy contributed to this story