Mon Mothma

Mon Mothma is a character from the Star Wars universe. She served as a political figure from the waning days of the Galactic Republic, is one of the founders of the Rebel Alliance, and is the first Chancellor of the New Republic. When the foundation of the Galactic Empire replaced the Galactic Republic that had existed for many millennia, she met with her allies in the Senate, such as Senators Padmé Amidala and Bail Organa.

Return of the Jedi
Mon Mothma was only seen once in Return of the Jedi, during the briefing of the Rebel's planned assault on the Empire's new battle station.

Rogue One
Mon Mothma is to appear in the upcoming movie, Rogue One. She will be portrayed by Genevieve O'Reilly, who was originally cast to portray the character in Revenge of the Sith.

Trivia

 * Mon Mothma appears briefly in Star Tours: The Adventures Continue at the end of the Geonosis segment when the StarSpeeder 1000 flies into the Rebel Alliance flagship docking bay. She is there with other Rebel Leaders.
 * Genevieve O'Reilly was originally cast as Mon Mothma in Revenge of the Sith. However, most of her scenes were cut from the final film.
 * Genevieve O'Reilly was chosen to portray the role due to her resemblance to Caroline Blakiston. Before filming, O'Reilly studied Blakiston's performance, hoping to capture the character's voice and mannerisms.
 * She is set to reprise her role, in Rogue One.

Palpatine
Mon initally respected Surpreme Chancellor Palpatine for his effective leadership. However, she became alarmed by his increasingly dictatorial authority and along with Bail Organa formed the Delagation of the 2,000 to demand an end to the Clone Wars and an end to his admendments. However, the attempt backfired: The Chancellor declared himself Emperor and had every member of the Delegation except for Bail, Mon (Since they didn't actually sign the Petition of the 2,000) and Padme branded traitors and arrested as enemies of the state. At Bail's urging, Mon voted for the Empire and dedicated her live to restoring the Republic and democracy the new Emperor destroyed. After the Rebel Network Bail Organa and Ahsoka Tano established was reorganized into the Rebel Alliance by the Corellian Treaty, Mon became it's leader and issued the Declaration of Rebellion calling for a revolution against the Empire to restore the Republic. When she learned that the Emperor would be onboard the under-constuction Death star II, Mon approved plans to attack it due to seeing it as a way to finally overthrow him. After the Alliance won the Battle of Endor, Mon announced the Birth of the New Galactic Republic and became it's first Chancellor and dedicated her years in office to ensuring that the New Republic never fell prey to the same incredible corruption and dangerous complacency that made Palpatine's rise to power possible.

Padmé Amidala
Mon and Padme respected each other greatly. After the Delegation of the 2,000 was formed, Mon recruited Padme to be it's spokewoman. During one Delegation meeting, Padme reminded her that Palpatine had a supermajority in the Senate on his side and urged that the Jedi be brought in but Mon refused stating it to be too extreme.

Bail Organa
Mon and Bail were both Loyalists who were dedicated to the Galactic Republic. After Chancellor Palpatine declared himself Emperor, both voted for the Empire at Padme's urging and dedicated themselves to overthrowing the self-made Emperor. Mon disagrred with taking the patient route Padme urged them to take and urged Bail to lead an open opposition against the Empire. When the Rebel Network Bail and Ahsoka Tano created was reorganized into the Rebel Alliance by he Corellian Treaty, Mon became it's leader and assumed leadership of the rebellion the Network started.