it might be mikhail Gorbachev and Nikitha Khruchev because thier era has been considered humiliating and low developmental years, because During Nikita Khrucheev's term, Soviets lost thier control over many soviet satellite states like greece uprising, failure in cuban missile crises, etc.
Mikhail Gorbhachov's liberal and westernised policies led to fall and disintegretion of soviet union into many independent republics - making United states of America as sole world super power for following years.