Grand Ayatollah Hossein-Ali Montazeri
Grand Ayatollah Hossein-Ali Montazeri is one of Iran's highest ranking theologians and at the same time one of the establishment's most outspoken critics.
Now in his eighties, he helped write the 1979 constitution and was once heir-apparent to the Islamic Republic's founder, Ayatollah Khomeini.
But in 1988 he fell out with Ayatollah Khomeini, just before the latter's death, for criticising official policy on human rights and other issues.
He was replaced as designated successor by the current supreme leader, Ayatollah Ali Khamenei.
Since then he has remained in the post of grand ayatollah, with a mass following among the faithful.
In 1997 he was placed under house arrest in the holy city of Qom for questioning the unaccountable rule exercised by the supreme leader.
On his release in January 2003 he vowed, despite ill health, to continue to speak his mind.
In September 2003 he told several hundred students in Qom that Iranians were dissatisfied with the ruling establishment, and that "the matter should be put to a popular vote".
And he condemned a crackdown by the judiciary on liberals and reformist publications as a "disgrace".
In a second attack on the leadership, just days later, he called the seizure in 1979 of the US embassy in Tehran a "big mistake" and urged a resumption of ties with Washington.
But he also told a Spanish daily that US forces should leave Iraq and hand over sovereignty to the Iraqis.
In October 2003 he continued his message of tolerance, saying the country's officials should "put aside their strictness".
He said President Khatami had failed to come up with promised reforms, causing "popular disappointment". And he questioned the legality of the country's revolutionary courts.
Shortly before the February 2004 elections, he told a meeting of the reformist Participation Front party that political parties should have the power to change a weak government.
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