Who is Khalil al-Hayya, the new Hamas chief Israel has been trying to kill since 2007?

Hamas' new chief Khalil al-Hayya will succeed Yahya al-Sinwar nearly two years after his assassination. One of Hamas' founding members, he gained prominence during Gaza war after heading Hamas' delegation in negotiations with Israel to reach a ceasefire and prisoner exchange deal. Al-Hayya, whom Israel is trying to kill since 2007, survived an Israeli assassination attempt in Qatar last year.