Beirut, Lebanon – The killing of Hezbollah Secretary-General Hassan Nasrallah leaves a vacuum inside a movement that has already had much of its leadership decapitated as a result of months of Israeli assassinations.

But Nasrallah’s death on Friday evening, during a massive Israeli attack on southern Beirut, marks the passing of not just a figurehead, but the man who embodied the Lebanese Shia movement in the eyes of its supporters and the wider region.

Nasrallah became secretary-general of Hezbollah in 1992 while he was in his 30s, and he led the movement for the majority of its existence. Finding a replacement of a similar stature will be difficult for Hezbollah, as it looks ahead to continued Israeli attacks and even a possible ground invasion of southern Lebanon.

There are, however, two leading figures thought to be in contention to be Nasrallah’s successor: Hashem Safieddine and Naim Qassem. Here’s what you need to know about them.

Hashem Safieddine

The head of Hezbollah’s executive council and a cousin of Nasrallah, Safieddine is widely thought to be in pole position to become the movement’s next secretary-general.

Born in 1964 in the southern village of Deir Qanoun en-Nahr, near Tyre, Safieddine studied theology together with Nasrallah in the two main centres of Shia religious learning, the Iraqi city of Najaf and Qom, in Iran. Both joined Hezbollah in the organisation’s early days.

Safieddine comes from a respected Shia family that has produced religious scholars and Lebanese parliamentarians, while his brother Abdullah serves as Hezbollah’s representative to Iran. Safieddine has his own close ties to Iran; his son, Redha, is married to the daughter of Qassem Soleimani, the top Iranian general killed in a US strike in 2020.

As well as his role in leading the executive council, Safieddine is also an important member of the group’s Shura Council, and the head of its Jihadi Council. That importance has made him an enemy to Hezbollah’s foreign adversaries. The United States and Saudi Arabia have designated Safieddine a terrorist and frozen his assets.

Naim Qassem

The 71-year-old is Hezbollah’s deputy secretary-general, and has often been referred to as the movement’s “number two”.

He was born in the Nabatieh governorate’s Kfar Kila, a southern Lebanese village that has suffered through many Israeli attacks, especially since last October.

Qassem has a long history in Shia political activism. In the 1970s, he joined the late Imam Musa al-Sadr’s Movement of the Dispossessed, which eventually became part of the Amal Movement, a Shia group in Lebanon. He later left Amal and went on to help found Hezbollah in the early 1980s, becoming one of the group’s foundational religious scholars.

One of Qassem’s religious mentors was the widely respected Ayatollah Mohammad Hussein Fadlallah, and Qassem himself has taught religious classes for decades in Beirut.

The secretive nature of a group like Hezbollah means not all his roles in the organisation are public knowledge. At one point, however, he oversaw part of Hezbollah’s educational network and has also been involved in overseeing the group’s parliamentary activities.

Qassem was elected deputy secretary-general in 1991, under then-Secretary-General Abbas al-Musawi, who was also assassinated by Israel.

He has played an important public-facing role in Hezbollah over the years, and is also a member of the group’s Shura Council.

He famously published a book called, Hezbollah, the Story from Within, in 2005, which was translated into several languages.