Disclaimer: I am not Rick Riordan or George Lucas.
Here are the characters in this story:
Percy Jackson - Luke Skywalker (age 16), Jedi demigod and Grand Admiral of the Imperial Remnant
Annabeth Chase - Mara Jade (age 16), Jedi demigod
Jason Grace - Jacen Solo (age 16), Grand Admiral of the Imperial Remnant
Piper McLean - Danni Quee (age 15), Jedi demigod
Leo Valdez - Ben Skywalker (age 15), Jedi demigod
Hazel Levesque - Tahiri Veila (age 13), Imperial demigod
Frank Zhang - Jagged Fel (age 16), Imperial demigod and general
Reyna Ramirez-Arellano - Tenel Ka Djo (age 16), Grand Admiral of the Imperial Remnant
Nico di Angelo - Kyp Durron (age 14), prisoner
Octavian - Thrackan Sal-Solo (age 18), Imperial senator and seer
Gleeson Hedge - Booster Terrik (age 104), Jedi recruiter
Thanatos - Xanatos (immortal), god of death (mention only)
Aphrodite / Venus - Yun-Q'aah / Lwyll (immortal), goddess of love
Dakota - Wedge Antilles (age 17), Imperial demigod and general
Nemesis - Yun-Harla (immortal), goddess of revenge
Tyson - Lowbacca (age 16), general
Gaea - Abeloth (immortal), mastermind
Hera / Juno - Shira / Lumiya (immortal), Queen of Tython (mention only)
Poseidon / Neptune - Vader (immortal), King of Kamino (mention only)
Chiron - Yoda (immortal), director of the Jedi Praxeum
Thalia Grace - Jaina Solo (immortal), Witch of Dathomir (mention only)
Grover Underwood - Corran Horn (age 33), Lord of the Wild (mention only)
Hades / Pluto - Bogan / Vitiate (immortal), King of the Netherworld (mention only)
Zeus / Jupiter - Sekot / Zonama (immortal), King of Tython (mention only)
Ares / Mars - Yun-Yammka / Yammosk (immortal), god of war (mention only)
Bacchus "Mr. D" - Ulic "Master Q" (immortal), god of wine
Ella - Qwi Xux (age unknown), Omwati
Arachne - Lomi Plo (immortal), weaver
Sally Jackson - Shmi Skywalker (age 45), mother of Luke Skywalker (mention only)
Porphyrion - Shimrra (immortal), Supreme Overlord of the Yuuzhan Vong (mention only)
Mrs. O'Leary - Drang (immortal), vornskr
Lupa - Vergere (immortal), Imperial instructor (mention only)
Hylla Ramirez-Arellano - Teneniel Djo (age 21), Hapan Queen Mother (mention only)
Alcyoneus - Shedao Shai (immortal), Yuuzhan Vong (mention only)
Sam Valdez Senior - Anakin Solo (deceased), ancestor of Ben Skywalker
Polybotes - Tsavong Lah (immortal), Yuuzhan Vong (mention only)
Arion - Tikk (immortal), uvak
Chrysaor - Antinnis Tremayne (immortal), pirate
Festus - Falcon (age unknown), mechanical dragon
Marie Levesque - Cassa Veila (deceased), mother of Tahiri Veila (mention only)
Emily Zhang - Syal Fel (deceased), mother of Jagged Fel (mention only)
Blackjack - R2-D2 (age unknown), aiwha
Phorcys - Xendor (immortal), sea god
Terminus - C-3PO (immortal), guardian of Bastion
Tempest - World Brain (amortal), dhuryam
Keto - Arden Lyn (immortal), sea goddess
Esperanza Valdez - Leia Amidala Skywalker (deceased), mother of Ben Skywalker
Medusa - Garowyn (immortal), Dathomirian (mention only)
Kronos / Saturn - Palpatine / Sidious (immortal), Sith Emperor (mention only)
Echo - Lujayne Forge (deceased), Melodie
Otis - Kunra (immortal), Yuuzhan Vong
Narcissus - Bror Jace (deceased), prince
Buford - Fiver (age unknown), mechanical table
Athena / Minerva - Ashla / Taselda (immortal), goddess of wisdom and war
Apollo - Yavin (immortal), god of prophecy (mention only)
Heracles / Hercules - Anakin / Skywalker (immortal), god of heroes
Grandmother Zhang - Zena Antilles (age 77), grandmother of Jagged Fel (mention only)
Skolopendra "Shrimpzilla" - Exogorth "Space Slug" (immortal), sea monster
Argentum - Chromium (age unknown), mechanical vornskr
Aurum - Aurodium (age unknown), mechanical vornskr
Ephialtes - Shoon-mi Esh (immortal), Yuuzhan Vong
Mrs. Chase - Jade (age 50), stepmother of Mara Jade
Rhea Silvia - Mazicia Organa (immortal), mother of Bail and Prestor Organa
Aphros - Gial Ackbar (immortal), Mon Calamari
Hannibal - Tarkin (age unknown), bantha
Achelous - Rush Clovis (immortal), sea god
Bill - Kit Fisto (age unknown), Mon Calamari hero (mention only)
Tiberinus - Ravelin (immortal), god of the Ravelin River
Rufus - Uldir Lochett (deceased), student at Yavin Academy
Hagno - Zannah (immortal), Melodie
Bythos - Cha Niathal (immortal), Mon Calamari
Esther - Jira (age 72), Theed citizen
Tristan McLean - Face Loran (age 40), actor
Triton - Starkiller (immortal), Prince of Kamino (mention only)
Glaucus - Bant Eerin (immortal), Mon Calamari hero (mention only)
Weissmuller - Jesmin Ackbar (deceased), Mon Calamari hero (mention only)
Ceres - Pelekotan (immortal), goddess of fertility (mention only)
Bellona - Augwynne (immortal), goddess of war (mention only)
Megara - Naberrie (deceased), late wife of Lord Skywalker (indirect mention only)
Deianira - Padmé (deceased), late wife of Lord Skywalker (mention only)
Hebe - Aldera (immortal), goddess of youth (mention only)
Nessus - Darovit (deceased), Chironian (mention only)
Mithras - Darth Millennial (immortal), god of war (mention only)
Perseus - Skywalker (deceased), Jedi demigod (mention only)
Tartarus - Yun-Yuuzhan (immortal), god of the Maw (mention only)
Khione - Nen Yim (immortal), Je'daii traitor (mention only)
Rachel Dare - Gaeriel Captison (age 16), Jedi Prophet (mention only)
Clarisse La Rue - Saba Sebatyne (age 17), Jedi demigod (mention only)
Drew Tanaka - Erisi Dlarit (age 16), Jedi demigod (mention only)
Enceladus - Onimi (immortal), Yuuzhan Vong (indirect mention only)
Artemis / Diana - Dathomir / Allya (immortal), goddess of the hunt (mention only)
Hephaestus / Vulcan - Yun-Ne'Shel / Kwaad (immortal), god of fire (mention only)
Midas - Zsinj (deceased), king (mention only)
Thomas McLean - Garik Loran (deceased), grandfather of Danni Quee (mention only)
Connor Stoll - Davin Fel (age 18), Jedi demigod (mention only)
Frederick Chase - (Talon) Karrde Jade (age 50), father of Mara Jade (mention only)
Luke Castellan - Jacen (Solo) Caedus (deceased), Jedi martyr (mention only)
Ethan Nakamura - Soontir Fel (deceased), Jedi martyr (indirect mention only)
Locations:
Camp Jupiter - Imperial Remnant (New Rome - Bastion)
Camp Half-Blood - Jedi Praxeum (mention only)
Camp Fish-Blood - Mon Calamari
California - Outer Rim (San Francisco - Braxant sector)
Berkeley - Sartinaynian
The Underworld - The Netherworld of the Force
Tartarus - The Maw
Kansas - Ruusan (Topeka - Olmondo)
Georgia - Naboo (Atlanta - Theed)
Utah - Dantooine
Olympus - Tython (mention only)
New York - Coruscant (mention only)
Alaska - Hoth (mention only)
Charleston - Bakura
Vancouver - Nirauan (mention only)
Manhattan - Galactic City (mention only)
Wolf House - Baanu Rass (mention only)
Rome - Old Bastion (Tiber River - Ravelin River)
Pillars of Hercules - Tatooine
Argo II- Millennium Falcon
Species:
Human - Human (Mortal - Mundane)
Satyr - Corellian
Olympian - Je'daii
Gigantes - Yuuzhan Vong
Titan - Sith (mention only)
Centaur - Chironian
Cyclops - Wookiee
Hellhound - Vornskr
Pegasus - Aiwha
Earthborn - Rakghoul
Harpy - Omwati
Nymph - Melodie
Ichthyocentaur - Mon Calamari
Horse - Uvak
Automaton - Droid
Gorgon - Dathomirian (mention only)
Telekhine - Noghri
Amazon - Hapan (mention only)
Lar - Force spirit
Hippocampus - Varactyl
Karpoi - Ewok (mention only)
Spider - Arachne
Anemoi thuelae / Ventus - Pazhkic Yuuzhan'tar al'tirrna / Dhuryam
Merpeople - Kaminoan
Stymphalian - Hawk-bat
Eidolon - Vagaari
Protogenoi - Celestials