Palpatine's first brother

Palpatine's first brother was one of at least two male children of Naboo aristocrat and head of House Palpatine Cosinga Palpatine and his wife, and brother to Palpatine, future Dark Lord of the Sith as Darth Sidious, Senator of Naboo, Supreme Chancellor of the Republic, and Emperor of the galaxy.

Biography
The youngest Palpatines resented their elder brother, and were present with their father, mother and bodyguards when they took him from Chandrila in the Palpatine family yacht. After the starship left Chandrila, Palpatine slaughtered his family, including his young brothers.

Palpatine remembered the lifeless forms of his siblings slumped on the starship floor every time his Sith master, [Darth Plagueis]], urged him to recall the murders in vivid detail as part of his training in the dark side.

Appearances

 * Star Wars: Darth Plagueis