Moqtada Sadr: Iraq's political, religious force
Today, as in past years following the overthrow of dictator Saddam Hussein, Iraq cannot ignore the grey-bearded preacher who once led a militia against American and Iraqi government forces.
Now he wants his Sadrist movement to lead the formation of the next government.
Final results in the October 10 parliamentary vote announced by the electoral commission gave the movement the largest bloc, 73 of parliament's 329 seats - up from the 54 it held before.
The results were announced over seven weeks after the polls, following fierce contestation by rival Shia blocs, some of which alleged fraud in the ballots.
The composition of the next government, and who will be prime minister, will depend on the outcome of negotiations between Sadr and his opponents.
One of them is Nuri al-Maliki, a pro-Iran figure who gained the premiership in 2006 with support from Sadr.
But the following year the cleric, who wears a black turban symbolic of a descendant of the Prophet Mohammed, ordered his followers to pull out of Maliki's cabinet, almost bringing down the government.
It was just one of several reversals the chameleon-like figure has made over the years, including in 2008 when he suspended activities of his Mahdi Army, which had been one of Iraq's most active and feared Shia militias.
Now he denounces the arms held by his adversaries, pro-Iran Shia parties linked to the Hashed al-Shaabi network of former paramilitary forces, with whom he must negotiate on forming a government.
"Civil peace will not be destabilised," he tweeted days after the vote, responding to calls on social media for violence, after the Hashed lost seats in the election.
Sadr also said "arms should be in the hands of the state, and their use outside of that framework prohibited", in a clear reference to the Hashed.
On November 18, he addressed "political forces who consider themselves the losers of these elections", and said their defeat "should not open a path to the ruin of Iraq's democratic process".
Sadr retains a devoted following of millions among the country's majority Shia population, including in the poor Baghdad district of Sadr City.
"He can occupy the streets. No one in Iraq can do it as well as him," said Hamdi Malik, of the Washington Institute for Near East Policy.
Perhaps uniquely in Iraq, Sadr has "a very obedient base" which also comprises a formidable online presence attacking his rivals in cyberspace, Malik said.
"Everything is revolving around him. That in Iraq is very important," he added.
During youth-led protests that erupted two years ago, Sadr sent thousands of followers to support the movement.
He then called them back, and later invited them to "relaunch the peaceful reformist revolution".
Hundreds of activists died in the protests. The movement has blamed pro-Iranian armed groups for the bloodshed.
Sadr initially said he would not take part in the parliamentary election but then reversed course, saying his movement would participate in order to help "end corruption".
"He might look a little bit crazy because of what he does," said Malik, but for his supporters "this craziness of withdrawing from the elections, coming back to the elections, threatening people, it's a sign of strength, charisma for many people".
Ben Robin-D'Cruz, a specialist in Shia movements at Aarhus University in Denmark, said Sadr "tries to position himself simultaneously in the centre of the political system while distancing himself from it".
His religious character, the researcher added, "allows him to create this illusion of transcending politics".
Born in 1974 in Kufa, near the holy Shia city of Najaf, Sadr is described by some who are close to him as easily angered.
He comes from an influential clerical family and left Iraq at the end of 2006 or the beginning of 2007, according to US and Iraqi officials, reportedly to pursue religious studies in the Iranian holy city of Qom.
But he has a checkered relationship with Iraq's neighbour.
Sadr's bloc contested the 2010 legislative election in an alliance with the Supreme Iraqi Islamic Council, another Shia group with links to Iran.
This time, though, he campaigned as a nationalist and criticised the influence of the Islamic republic.
Sadr wants an accommodation with Iran that would allow him to compete against its allies politically without the constraints currently imposed by the "greater coercive power" of the armed pro-Iran factions, Robin-D'Cruz said.
"But the Iranians have been reluctant to do that, because they don't want to empower Sadr and they don't consider him reliable," the analyst said.