Darth Jar Jar, known publicly as the oft-clumsy Jar Jar Binks, was a Gungan Senator from Naboo and a secret Sith Lord who was trained by a mysterious holocron in the swamps of his homeland. Known to the vast criminal underworld as Palo, he often runs his network through his proxy, a rebuilt HK-47 assassin/protocol droid named Meatbag.
After surviving the Battle of Naboo and befriending the Jedi, Jar Jar became a Representative of Naboo (then promoted years later to Senator when Padme Amidala returned to Naboo) where he helped give emergency powers to Sheev Palpatine to become Supreme Chancellor of the Republic with the ability to wage war.
This turning point marked the decline of the Republic and rise of the Empire. Jar Jar's influential play was heavily rewarded by Palpatine, allowing him access to the Emperor's inner circle and affording him many designations to chairman of various powerful political committees. It was through these committees that the shrewd Gungan was able to make alliances and broker deals.
When the Emperor instituted Order 66 and began to tighten his grip on the remaining Senators during the last moments of the Republic, Jar Jar left Coruscant to be at the helm of his lucrative enterprise and focus on learning more of the Dark Arts from his shadowy benefactor.