Final answer:
Cleisthenes took power in 508 B.C. and established democracy in Athens, implementing reforms that allowed all male citizens to participate in government, ultimately shaping Athenian politics and society.
Step-by-step explanation:
The individual who took power in 508 B.C. and created a democracy in Athens was Cleisthenes. He was appointed by the Athenian assembly and took the radical step of allowing all male citizens, including the free but poor citizens, to vote in public matters and to be eligible for public office. Cleisthenes' reforms included having lawmakers chosen by lot and creating new "tribes" that incorporated men from various backgrounds to promote a unified Athenian identity.
Before Cleisthenes, the Athenian ruler Solon had laid the groundwork for a more inclusively governing system around 600 BCE by allowing all male citizens to vote on local leaders and attempting to end debt slavery. Later, during the Golden Age of Athens, Pericles further developed Athenian democracy, by implementing reforms such as allowing thetes to occupy public office and the creation of a salary for citizens serving as jurors.