Bandit Nine

Bandit Nine are a non-canon group of bandits led by Gillian.

Members
The only known member is Gillian.

Past
At some point in the past, Gillian left the Goa Kingdom and began traveling to various islands, uniting various bandit groups along the way. Over time, he managed to unite nine bandit groups, merging into them Bandit Nine and gaining the epithet himself.

One Piece Odyssey
While on Water 7, Gillian ran into the Straw Hat Pirates, declaring that he would get revenge for his humiliation at Luffy's hands. After getting over the dismay of Luffy not remembering him, Gillian attacked the Straw Hats, but was quickly defeated. He was handed over to Margin, who claimed his bounty.

Meanwhile, the rest of the Bandit Nine members remained in hiding in various mountains, out of contact with Gillian.

Whether Bandit Nine are still active after Gillian joined the Bounty Pirates is unknown.