Lina Ron, a vocal supporter of President Hugo Chavez who led radical street groups, died of a heart attack Saturday, Venezuela's government said. She was 51.
Chavez praised her as "true soldier of the people." In a Twitter post, Chavez said: "A Complete Revolutionary. Let's follow her example!"
Information Minister Andres Izarra confirmed Ron's death, saying she had no vital signs when she arrived at a Caracas hospital. "Honor and glory to Lina Ron," Izarra said on Twitter.
Ron led groups of Chavez supporters that were involved in attacks on opposition protests, and she repeatedly said she would take up arms if necessary to defend Chavez and his socialist movement.
With platinum-blond hair and a tough-talking nature, Ron soon became a household name in Venezuela within the first few years after Chavez took office in 1999. She founded the small political party Venezuelan Popular Union and was for years a prominent voice in the radical wing of Chavez's movement.
Ron's supporters mourned her death in a Caracas plaza on Saturday, some holding the flags of her political party.
Chavez once said Ron was "a good woman, but she tends toward anarchy."
The president publicly opposed some of her tactics. She faced various charges related to her involvement in disturbances.
In 2009, a court upheld criminal charges against Ron including assault and illegal use of a firearm for her role in an attack in which her group hurled tear gas canisters at the studios of the television station Globovision. She also led a group that stormed and temporarily occupied the offices of the Vatican's representative in Caracas in 2008.
In an earlier protest that drew widespread criticism, she burned a U.S. flag shortly after the 9/11 terrorist attack.
In a 2002 interview with The Associated Press, Ron described herself as a "social fighter."
"I'm the ugly part of the process, the one who gets the disagreeable part _ confronting" Chavez's enemies, Ron said.
Some government opponents have said Ron was useful for Chavez in that she and her allies would regularly intimidate members of the opposition while government officials publicly distanced themselves from her.