firebrand:
(plural: ‘firebrands‘; pronunciation: ‘fire…brand’ — for the right pronunciation, please click here)
a person, especially a popular person in politics, who starts up trouble or causes others to revolt;
a person who speaks out his/her opinions frankly and boldly, causing anger and excitement among others,

Uma Bharthi, a female political firebrand
After being an ordinary worker in a charity organisation for quite some time, Robert has become a firebrand social activist in the country, fighting for the rights of the homeless.
Though there are several angry young men in politics who fought their own party members on some issues, Gerald is one firebrand whom even the top dogs of the party hesitate to argue lest they should be shouted down by this young man.
Susan used to be one of the female firebrands in the field of higher education, expressing her opinions and exposing the lapses in running the universities, until the tragedy in which she lost two of her children in a road accident struck her and doused the fire in her.
