Sebulba is a famous podracer on Tatooine. He's famous because he always wins; he always wins because he cheats. This isn't Konami Code-type cheating either. Sebulba is a brutal crook who sabotages the other racers' pods to violent results.
In terms of story, he provides the Ivan Drago to Anakin's Rocky, the Johnny Lawrence to his Daniel-san, and the Shooter McGavin to his Happy Gilmore. Point is: he's the dirty, cheating opponent Anakin must beat to win the day. True to the sports film formula, Anakin manages to beat Sebulba by playing fair, and Sebulba's cheating ultimately loses him the race.
Supreme Chancellor Finis Valorum
Valorum serves as the Galactic Republic's Supreme Chancellor, the Star Wars universe's head of state. He supports Queen Amidala and tries to bring the Trade Federation's blockade to a peaceful resolution through negotiations. First, he sends Qui-Gon and Obi-Wan as ambassadors, and when that fails, he brings Amidala to state her allegations to the Senate itself.
It doesn't end well for him though. Despite his power, he plays by the political rules and can't juke Senator Palpatine's behind-the-scenes scheming. After Padmé calls for a vote of no confidence in his leadership, Valorum is impeached and his successor proves to be none other than Palpatine.
Boy, Queen Amidala sure looks a lot like Keira Knightly, doesn't she? That's because the "queen" we see for most of the film isn't Queen Amidala but her bodyguard Sabé—who just happens to be played by Keira Knightly.
Sabé is a loyal companion to Padmé. By switching places with her, Sabé willingly makes herself the target of Viceroy Gunray's plots in lieu of her liege.
Her willingness to put herself in danger to protect her queen is most evident at the film's conclusion. When Gunray finally captures Padmé, Sabé appears dressed as the queen. Believing Padmé to be a diversion, Gunray sends his bodyguard droids to hunt down Sabé. This gives Padmé the opportunity to capture Gunray and bring an end to the occupation of Naboo.
Fode and Beed
Fode and Beed are (is?) the two-headed announcers of the Tatooine pod races. Fode is the one who speaks in Basic—the Star Wars galaxy's equivalent of English—and Beed is the one who speaks in Huttese. Yep, the Hutts are apparently so rich and powerful that they own their own language.
Ric Olié is the starship pilot of Queen Amidala's Naboo cruiser. Yeah, we were surprised to find he had a name, too. He must be excellent at his job, because he runs the Trade Federation's blockade twice.