"Shah" is the title given to emperors, kings, and lords of Iran. Not exactly identified as a king, but the Shah is more seen of as a ruler of one part of a nation.
The Shah is known to Iranians as what we call a king. He was a monarch and sometimes known to people as a "royal dictator" or a "one man ruler". He would very often employ secret police, execution, and torture to stifle political dissent.
The Shah of Iran, Reza Shah, came into power during World War 2. In 1941, he was crowned Shah and had taken his fathers role. He'd later became trapped in a struggle with the Soviet Tudeh Party, who wanted social revolution without a Shah.
His popularity had began to decrease when people realized his authority knew no bounds. This caused him to start becoming increasingly repressive, leading to him using his secret police, hoping he could stop domestic conflicts.
When the Soviet Union had started helping the Persian Communist Party, Iran brought the Issue to the former United Nations(UN) and the Sovet troops left Azerbaijan, causing the Shah's popularity to rise. He'd become more well known than before.
In 1979, the last Shah of Iran was forced to leave the country after the widespread strike demonstration. In Tehran, Iranian students had seized 63 hostages, demanding that the Shah return from the United States to be given trial. April 25th, 1980, the Exiled Shah died of cancer in Egypt.