Reagan, Thatcher, King Saud and the Pope John Paul II actually. But Gorbachev certainly helped....
Gorbachev had no choice.
If it was up to him, his economy wouldn’t have been in tatters. Reagan fundamentally understood you cannot have economic freedom without political freedom, so he attacked the Soviet Union on all economic fronts, vibrant capitalism, the world oil market, the space race, technology, sabotage of the Siberian pipeline, on and on.
Reagan forced the Soviet Union into attempting economic reform, and the international communist empire imploded as a result.
Without Reagan, there is no Gorbachev.