The shadowy mastermind behind Hamas’ sneak weekend slaughter in Israel is a one-armed, one-legged psycho nicknamed “the cat with nine lives’’ because he’s dodged so many Israeli assassination attempts.

“Mohammed Deif,” the pseudonym used by the fearsome head of the Palestinian terror group’s military wing, chillingly warned “the enemy” that they will soon be “held to account” as Hamas launched its unprecedented attack on Israel, kicking off a war Saturday that has already left more than 1,000 Israelis and 765 Palestinians dead.

“In light of the continuing crimes against our people, in light of the orgy of occupation and its denial of international laws and resolutions, and in light of American and Western support, we’ve decided to put an end to all this,” the wheelchair-bound terror chief and former bomb-maker said in a broadcast Saturday, according to Financial Review.

“So that the enemy understands that he can no longer reveal without being held to account,” added Deif, whose last name means “guest” in Arabic — an apparent reference to him moving around so much staying with different operatives to escape detection.

As Deif’s dark message was disseminated across the airwaves, his terror organization launched thousands of rockets at Israel while its fighters infiltrated the border, including some on motorized paragliders — initiating the largest attack on the Jewish state in 50 years.

Included in the horrific climbing death toll were at least 11 Americans. Other US citizens remain missing, and President Biden said Monday that at least some of them are “likely” among the 130 or so people believed to have been taken hostage by the terrorists.

Deif has remained in the shadows for decades despite Israel’s best efforts to take him down at least five times in assassination attempts. He is believed to remain in a wheelchair after losing an arm and a leg in a failed assassination attempt years ago.

Saturday’s attack may turn the terrorist commander into a figure “like a god to the young,” according to Mkhaimar Abusada, a professor of politics at Al-Azhar University in Gaza.

“Even before this, Deif was like a sacred personality and very much respected both within Hamas and by the Palestinians,” Abusada told the Financial Review.

Before Deif morphed into an elusive Palestinian military figure, taking on his pseudonym and appearing in a few grainy photographs over the years, he was known as Mohammed Diab Ibrahim al-Masri in the Khan Younis refugee camp during the 1960s, according to an Israeli official familiar with his security file.

Even then, he had a reputation as someone willing to use violence as a means to end the Israeli-Arab conflict, Israeli and Palestinian analysts said, according to the outlet.

He also viewed the Oslo Accords — which was the first time Israel and the Palestine Liberation Organisation recognized the other — as a deep betrayal of the resistance movement.

“Deif has tried to start the second war [against] Israeli independence,” said Eyal Rosen, a colonel in the Israeli army’s reserves who in a previous role focused on the Gaza Strip, to the Financial Review.

He also viewed the Oslo Accords — which was the first time Israel and the Palestine Liberation Organisation recognized the other — as a deep betrayal of the resistance movement.

“The main goal is – by steps – to destroy Israel. This is one of the first steps – this is just the beginning,” Rosen said of Deif’s latest maneuver.

By the time Hamas was formed in the late 1980s, Deif shared a prison cell with Ghazi Hamad, who now serves as a Hamas politburo member.

“From the beginning of his life in Hamas, he was focused on the military track,” Hamad said.

But the terror chief also allegedly had a soft side.

“He was very kind, all the time a patriot who would make little cartoons to make us laugh,” Hamad said.

Still, Deif’s kind streak was seemingly short-lived, as Israel has blamed him for killing dozens of people in previous suicide bombings, including a massive surge in 1996 that killed more than 50 civilians.

He warned Saturday in his recorded broadcast announcement shared on Hamas media, “Enough is enough.