Theodora, the Byzantine Empress.

She is, in a way responsible for the shape of the modern world.

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She was a whore, but married Emperor Justinian I.

When the Nika riots happened Justininan wanted to flee Constantinople, but she convinced him and other officials not to leave. Instead the quelled the riots and rebuilt Constantinople.

Effect 1 - Justinian had the Hagia Sophia built. When the Muslims took Constantinople, they liked it so much that they modeled most mosques after it, including the dome and the minarets. As a result of Theodora domes and minarets are main features of the Muslim world.

Many Russian Orthodox churches were also modeled after it. The onion domes in St. Basil's, for example, are results of imitation of the Hagia Sofia's dome.

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Effect 2A - Justinian compiled Roman law into the Justinian Codex. What is significant is he sorted the law into ordered categories, which is the model for organizing modern Western law. This innovation enabled later societies to have more complex, yet more consistent bodies of law.

Effect 2B - The Justinian Codex was a major contributor to English Common Law. Because of the British Colonial Period, that body of law, including Justinian's contribution, was spread worldwide, including to the US, which spread it further.

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In fact, almost the only places whose laws are not influenced by the Codex are the Muslim countries (which have Sharia) which are instead architecturally influenced by the Hagia Sofia.

All because Theodora refused to leave Constantinople during the riots, stop being an empress, or go back to being a whore.

Abraham Lincoln. He freed the slaves from the Democrats and they martyred him for it.

I have way too many favorites to just pick one but I'll pick Talleyrand (Napoleon's foreign minister). Believing that Napoleon would lead his country to ruin he decided to turn against him. By conspiring with his personal worst enemy, Napoleon's chief of secret police Joseph Fouche (who had previously tried to assassinate Talleyrand by the way), he managed to overthrow Napoleon.

Napoleon was then exiled to Elba, close to Italy. Talleyrand foresaw that Napoleon would inevitably escape and return to power and so he tried in vain to persuade the European powers to exile him further away. Failing to persuade them, he worked quietly with others to engineer Napoleon's escape. Upon his escape Napoleon immediately regained power due to his incredible reputation and popularity; the current king even had to flee the country. However France was bankrupt and exhausted from the preceding wars and after a mere hundred days he was utterly defeated at Waterloo. Thus Talleyrand got his way and Napoleon was exiled further away, this time with no chance of escape.

By far, Pericles. And Julius Caesar too but mostly Pericles. Why? Because Pericles was a charismatic leader, he persevered, and he fought the Persians. And the other Greeks too but I mostly care about the Persian part.