Shokri Belaid, a lawyer born in 1964 in the Tunisian town of Jebel Jelloud, was a staunch critic of Zine El Abidine Ben Ali, the country's former authoritarian ruler, who was overthrown as a result of the revolution in 2010-2011.
Belaid denounced the clampdown on miners in 2008 and after the revolution, he was a leading member of the Popular Front, an umbrella organisation of 12 opposition parties, including his own Democratic Patriots.
Al Jazeera's Hashem Ahelbarra said that the coalition is "a gathering of leftists, secular activists totally opposed to the policies of the predominantly Islamist government in Tunisia".
"[Belaid] has been a vocal critic of the government, saying that the outcome of the revolution in Tunisia was the growing power and influence of the Islamists. He's been reiterating the same message of the Islamists being a threat to democracy in the country, and said that what the country needs to have instead is a democratic government which has been deeply entrenched in Tunisia to prevail," Ahelbarra said.
He said Belaid's position earned him many opponents within the Tunisian political society - particularly among conservatives and Islamists.
Earlier this week, Belaid had said that the committees established out of the revolution were a "tool" used by the government and Islamists to get rid of the coalition party.
He was fatally shot outside his home in El Menzah, near Tunis, on February 6, 2013, with bullets to his head and chest.
Rachid Ghannouchi, the leader of the ruling Ennahda Party, Tunisian President Moncef Marzouki and French President Francois Hollande were among the first to condemn the assassination.