Gorosei

The Five Star Elders are the leaders of the World Government in One Piece. They can be considered the primary antagonists of the series, as they rule the most corrupt organization in the One Piece World.

Abilities
As the leaders of the World Government, the Gorosei has unlimited political power in the One Piece world. They are the leaders of the World Government and they have control over the 170 allied nations. The Gorosei have final say over anything since they have the power to veto the Fleet Admiral's commands. They also have higher power than the Celestial Dragons.

When it comes to physical abilities and prowess, not much is known about them. However, one of the members was seen with a sword which may imply that the member is skilled with the sword.

Past
Not much is known about how these members became the leaders of the World Government or why they became the leaders, but for many years they have been leading the World Government.

Ohara Incident
Since the archeologists of Ohara have been studying the Poneglyphs, the Gorosei decided that this was too dangerous beacuse they did not the world to know about the World Government's past. To avoid any upcoming problems, the Gorosei finally decided to initiated a buster call (or a destructive Navy attack) on the small island.

Sky Island Saga
They first appear talking about who might take Crocodile's seat as the new Shichibukai. They also went on about the interactions with the Yonko.

Water 7 Saga
The Gorosei was commenting on Aokiji and his position as an Admiral. They were still interested in the interactions between the Yonko.

Summit War Saga
After the Whitebeard war, they were concerned about the condition of the world. They appeared to be upset about Jinbe since he left the Shichibukai; the Gorosei sees this as conflict between humans and fishmen. They continue to talk about the danger of Luffy and Blackbeard since they both have the Will of the D.

During Time Skip
After Sengoku step down from the position of Fleet Admiral, the Gorosei nominated Akainu as his successor. Akainu won the position after defeating Aokiji in a duel (causing the latter to leave the marines).

Pirate Alliance Saga
They seemed to be confused and worried about Donquixote Doflamingo's position as Shichibukai and his interaction between Luffy and Law. In an argument with Akainu, it was revealed that they had lied to the world about Doflamingo leaving the Shichibukai. They were shock to hear that Luffy defeated Doflamingo.

Trivia

 * They are one of the few characters to have appeared before but not have their names introduced. Their first appearance was Chapter 233.