Leaders and politicians around the world have expressed their condolences as news spread that the last Soviet leader, Mikhail Gorbachev, whose reforms helped end the Cold War and free Eastern Europe from communism, but also led to the collapse of the Soviet Union, died overnight at the age of 91.

Some in Russia and elsewhere took to social media to criticize the man they blamed for making Russia a second-rate power, a feeling that eventually led to the rise of President Vladimir Putin, who has tried for the past quarter-century to restore Russia to its former glory and beyond.

Condolences Pour in as Last Soviet Leader Gorbachev Dies At 91

Gorbachev died late on Monday "after a serious and prolonged illness," the Central Clinical Hospital in Moscow said.

Condolences Pour in as Last Soviet Leader Gorbachev Dies At 91

The news triggered an immediate outpouring of praise from global leaders far and wide for the man who helped trigger a a pivotal turning point in world history.

Condolences Pour in as Last Soviet Leader Gorbachev Dies At 91

Gorbachev was "a one-of-a-kind statesman who changed the course of history. He did more than any other individual to bring about the peaceful end of the Cold War," UN Secretary-General Antonio Guterres said. "The world has lost a towering global leader, committed multilateralist, and tireless advocate for peace."

A trained lawyer by profession, Gorbachev took over the Communist Party and Soviet leadership in 1985 and presided over six turbulent years that saw the fall of the Iron Curtain, the reunification of Germany, and ultimately the Soviet demise that Putin has since called "the greatest geopolitical catastrophe" of the 20th century.

Gorbachev famously ushered in "glasnost" and "perestroika" in an effort to keep the struggling Soviet Union alive.

German Chancellor Olaf Scholz on August 31 hailed Gorbachev's role in reuniting Germany but lamented that his attempt to establish an enduring democracy in Russia had "failed," a thinly veiled criticism of Putin, who has been roundly criticized by the international community for cracking down on civil society in recent years.

"The democracy movements in Central and Eastern Europe benefited from the fact he was in power then in Russia," Scholz said. However, Gorbachev "died at a time in which democracy has failed in Russia."

Added Britain's outgoing Prime Minister Boris Johnson: "In a time of Putin's aggression in Ukraine, his tireless commitment to opening up Soviet society remains an example to us all."

In a statement issued in the early hours of Tuesday, U.S. President Joe Biden called Gorbachev a "rare leader -- one with the imagination to see that a different future was possible and the courage to risk his entire career to achieve it. The result was a safer world and greater freedom for millions of people."

French President Emmanuel Macron praised Gorbachev as a "man of peace" whose decision opened a "path of freedom" for Russians. "His commitment to peace in Europe changed our common history," Macron said on Twitter.

China praised Gorbachev for his part in improving ties between Beijing and Moscow in the 1980s and '90s after decades of tensions over ideological differences and competing geopolitical interests.

"Mikhail Gorbachev made positive contributions to the normalization of Sino-Soviet relations," Foreign Ministry spokesman Zhao Lijian told a press conference, adding: "We mourn his death and express our condolences to his family."

At home, however, Gorbachev's legacy was being spoken of in a different tone.

The developments in Eastern Europe triggered by Gorbachev helped fuel aspirations for democracy and autonomy among the 15 republics of the Soviet Union, which fell apart, sometimes violently.

In January 1991, Soviet troops killed 14 people at Lithuania's main TV tower in an attack that Gorbachev denied ordering. In Latvia, five demonstrators were killed by Soviet special forces.

“Lithuanians will not glorify Gorbachev," tweeted Lithuanian Foreign Minister Gabrielius Landsbergis, the son of Vytautas Landsbergis, who led Lithuania’s independence movement in the early 1990s.

"We will never forget the simple fact that his army murdered civilians to prolong his regime’s occupation of our country. His soldiers fired on our unarmed protesters and crushed them under his tanks. That is how we will remember him,” he added.

Gorbachev was politically debilitated by a hard-line coup in August 1991 that failed in large part due to a popular resistance led by Boris Yeltsin.

A week later, Gorbachev resigned as Communist Party general secretary.

In late December 1991, his resignation as president of the Union of Soviet Socialist Republics effectively spelled the end of the Soviet empire.

Putin paid tribute to Gorbachev for his reform efforts and humanitarian work.