First, "Palo" (Gungan for "friend") is the underground alias used by Jar Jar Binks to run his criminal organization across the galaxy from his comfortable Senate seat in Coruscant.
The Palo Syndicate is a ring of criminals, bosses and warlords who conduct business beneath the Republic (and later, the Imperial) radar.
Palo's proxy, a HK-47 assassin droid named Meatbag, handles collections and is considered to be the "face" of The Palo Syndicate since very few people have ever met Palo, and even fewer have lived to tell about it.
While the majority of The Palo Syndicate members are unknown, a few notable characters are the con artist duo Dannl Faytonni and Achk Med-Beq, the bounty hunter Djas Puhr and the galaxy-renowned Hutt cartel leader Jabba Desilijic Tiure.
More can be be found about The Palo Syndicate in the story Silencing the Gungan: A Darth Jar Jar Tale.