Abdel Aziz al-Rantissi, who was killed in an Israeli missile strike on 17 April, had been one of the most forceful spokesmen against compromise with Israel.
Rantissi: An uncompromising figure
Rantissi took over the leadership of the militant Islamic movement Hamas in Gaza after the killing of the group's spiritual leader Sheikh Ahmed Yassin in March.
He consistently argued that Palestinians have a right to resist Israel by any and all means, including the suicide bombing of civilians.
"They are not terrorism," he said of such attacks.
"They are a response to Israeli terrorism, individual and governmental, against Palestinian civilians," he told the Arabic newspaper Kut al-Arab in 1998.
Rantissi described himself as one of seven founders of Hamas.
Khaled Meshaal - Hamas' politburo chief living in exile - was declared the group's overall leader after Sheikh Yassin was killed in an Israeli missile strike.
Rantissi had in 2003 survived an earlier assassination, but died in hospital after an Israeli attack on his vehicle in April 2004.
He once said that he did not fear assassination.
"I am not afraid. I am looking to be a martyr. Why? Because I believe that the last day for me is not in the hand of Sharon, but in the hand of Allah."
Rantissi was born in 1947 near Ashkelon, in what is now Israel. The town, then known as Yebna, is now known by its Hebrew name, Yavneh.
In 1948 he was one of the 200,000 or so Palestinians who became refugees in Gaza after Israel's confrontation with the surrounding Arab states.
He was brought up in the refugee camps of the Gaza Strip, at first under Egyptian control and then, after 1967, under Israeli occupation.
Rantissi he trained to be a paediatrician. While studying in Egypt in the 1970s, he became attracted to the Muslim Brotherhood, an Islamic movement outlawed in the country.
He rose to prominence with Hamas during the first Palestinian intifada in the late 1980s and early 1990s.
He was arrested by Israel several times during the intifada, spending as much as two and a half years in prison on one occasion.
Then, in late 1992, he was among more than 400 Islamic militants deported to Lebanon. He became a spokesman for the deportees in his camp, Marj al-Zahour.
After his return to Gaza, he proved no more popular with Yasser Arafat's Palestinian Authority than he had been with the Israeli government.
Palestinian officials arrested him in 1998 after he demanded that a number of senior Palestinian Authority figures resign.
He accused the Palestinian Authority of collaborating with Israel in causing the death of a Hamas bomb maker.
The Palestinian High Court of Justice ordered his release some two months after he was arrested.
He remained a regular critic of the Palestinian Authority, condemning it for its apparent willingness to compromise with Israel as part of the roadmap peace plan.
He resisted former Palestinian Prime Minister Mahmoud Abbas's call for a ceasefire to give the US-backed peace plan, known as the roadmap, a chance to work.
He blasted Prime Minister Abbas - also known as Abu Mazen - for participating in a conference with Israeli Prime Minister Ariel Sharon and US President George W Bush in Jordan in June 2003.
The Palestinian prime minister's "whole speech was a terrible mistake; even Abu Mazen's ministers, even his son opposed it", Rantissi told the Jerusalem Post newspaper.
"It was unacceptable," he said.