The top figures in the militant group Hamas after the assassination Sunday of its leader, Abdel Aziz Rantisi.

-- Mahmoud Zahar: A Hamas spokesman, the 53-year-old Zahar is considered a hard-liner. Zahar was the personal physician of Hamas founder Sheik Ahmed Yassin, who was killed by the Israelis on March 22. Zahar served as Hamas' liaison with the PLO in the mid-1990s but now opposes compromise with the Palestinian Authority. Zahar has been imprisoned by Israel and has been jailed repeatedly by the Palestinian Authority.

-- Ismail Hanieh: A top aide to Yassin and like Zahar he is a member of Hamas' decision-making political bureau. Hanieh is considered more pragmatic, although and other Hamas leaders all advocate the destruction of Israel. Hanieh is Hamas' go-between with the Palestinian Authority.

-- Khaled Mashaal: Mashaal, a physics teacher born in the West Bank, oversees Hamas' political bureau from Damascus, Syria. Mashaal, in his late 40s, helped negotiate a truce last summer that temporarily halted Palestinians attacks on Israel. Israel has accused Mashaal of masterminding suicide bombings. In 1997, agents from Israel's Mossad injected him with poison darts in Jordan. He survived after Jordan's King Hussein coerced Israel into sending the antidote. In 1999, Mashaal was expelled from Jordan and moved to Syria.

-- Moussa Abu Marzook: Abu Marzook, in his early 50s, Mashaal's deputy in the political bureau. The U.S.-educated Abu Marzook, who holds a Ph.D. in industrial engineering, lived in the United States for 15 years. In 1995, he was detained by U.S. authorities on suspicion of involvement in terrorism. He was expelled to Jordan, and later sent by Jordan to Syria. Like Mashaal, Abu Marzook is unlikely to be targeted by Israel because of his location.