These are only confirmed names by official LFL Sources. So no invented names ...

The Phantom Menace
Supreme Chancellor Valorum
Mas Amedda
Tei Saria

Palpatine: Chommel Sector
Lott Dod: Neimoidia (and occupied worlds)
Mik Regrap: Neimoidian Aide with oval shaped hat.
Aks Moe: Malastare
Baskol Yeesrim: Malastare
Ainlee Teem: Malastare
Orn Free Taa: Ryloth
Pampy: Ryloth
Supi: Ryloth
Bail Antilles: Alderaan
Agrippa Aldrete: Alderaan
Liana Merian: Alderaan
Edcel Bar Gane: Roona
Horox Ryyder: Gravlex Med
Mot Not Rab: Unknown homeplanet
Passel Argente: Kooriva
Tandau Bendon: Ithor
Tikkes: Calamari
Yarua: Kashyyyk
Yeb Yeb Ademthorn: Makem Te
Toonbuck Toora: Sy Myrth
Grebleips (E.T. Senator): Brodo Asogi

Unknown: Neimoidian aides, Ithorian aides, Aqualish Senator & aides, Rodian Senator & aides, Wookiee aides, Sy Myrthian aide, Roona aide, Aleena, etc ...

Attack of the Clones
Supreme Chancellor Palpatine
Mas Amedda
Sly Moore
Dar Wac

Padmé Amidala: Chommel Sector
Jar Jar Binks: Chommel Sector
Orn Free Taa: Ryloth
Pampy: Ryloth
Supi: Ryloth
Bail Organa: Alderaan
Ister Paddie: Sermeria
Ask Aak: Malastare
Lexi Dio: Uyter
Ronet Coor: Iseno
Tundra Dowmeia: Calamari
Nor Wed: Calamari
Zil Topur: Calamari
Onoconda Farr: Rodia
Tox Don: Rodia
Pa Dua: Rodia
Simon Greyshade: Vorzyd
Gorothin Vagger: Andoan Free Colonies
Darsana: Glee Anselm
Toonuck Toora: Sy Myrth
Zo Howler: Gravlex Med
Fo Kuna: Gravlex Med

Revenge of the Sith:
Supreme Chancellor Palpatine
Mas Amedda
Sly Moore

Padmé Amidala: Chommel Sector
Jar Jar Binks: Chommel Sector
Bail Organa: Alderaan
Mon Mothma: Chandrila
Sheltay Retrac: Alderaan
Giddean Danu: Kuat
Bana Breemu: Humbarine
Fang Zar: Sern Prime
Fema Baab: Bajic Sector
Nee Alavar: Lorrd
Malé-Dee: Uyter
Chi Eekway: Wroona
Terr Taneel: Neelanon
Meena Tills: Calamari
Tundra Dowmeia: Calamari
Orn Free Taa: Ryloth
Veedaaz Awmeth: Sarrish / Vensensor Sector
Gume Saam: Tibrin
Solipo Yeb: Andalia (?)
Ask Aak: Malastare
Sweitt Concorkill: Sembla
Gem Sirrom: Unknown
Ivor Drake: Kestos Minor (blonde human female)
Tanner Cadaman: Feenix (greying human male)
Nep Creip (Dark skinned human): Unknown
Cellheim Anujo (covered by a black veil): Unknown
Silya Shessaun: Thesme Sector
Eeusu Estornii: Ord Zeuol

Unknown Senators when Palpatine arrives on Coruscant

(*) This information is not officially published in any 'SW'-book, but is derived from an official 'E.T' book. Senator Grebleips is an official Senator from the prequels, but it is not known if it's really the 'E.T' senator, although it is widely presumed since his name is Spielberg spelled backwards.