With her distinctive blonde braid, wrapped neatly around her head, Ukraine's Yulia Tymoshenko led her country during the 2004 "Orange Revolution" which overturned a fraudulent election victory for Viktor Yanukovich.
After a divisive term as prime minister she narrowly lost to him in an election in 2010.
Just a year later, Tymoshenko was convicted of "illegally agreeing a gas deal with Russia" during her time as the Prime Minister and spend the last two and half years locked up in a hospital under prison guard.
The EU had long considered the 53-year-old opposition leader a political prisoner. Her freedom was one of the main demands it had for closer ties with Ukraine during years of negotiations that ended when Yanukovich abruptly turned towards Moscow in November.
Tymoshenko's release was greeted with enthusiasm, reflecting the hopes she can transform Ukraine by giving the opposition a single leader and potential future president, although Klitschko and others also have claims.
"Our homeland will from today on be able to see the sun and sky as a dictatorship has ended," she told reporters as she prepared to head for Kiev to visit Independence Square," she said.
Before joining politics, Tymoshenko was the president of United Energy Systems of Ukraine, the main importer of Russian natural gas.