Final answer:
Cleisthenes is credited with significant reforms in 508 BCE that laid the foundation for the first 'real' democracy in Athens by allowing all male citizens to vote and hold public office.
Step-by-step explanation:
The Athenian leader who played an instrumental role in the founding of a democracy in Athens in the late sixth century BCE was Cleisthenes. In 508 BCE, Cleisthenes was appointed by the Athenian assembly and made significant reforms which included allowing all male citizens to have a vote in public matters and becoming eligible for public office. Additionally Cleisthenes created a new council and reorganized the Athenian citizens into ten new tribes, introducing a system that would lay the foundation for the first 'real' democracy in history.