Many characters go by many different names, so to make things easier, consider this a compendium of all the names for the characters, and their aliases to better comprehend the lore

Pope Francis
Aliases: The Pope Francis, Fran, Frolo, The Pope Who Likes Poop, The Very Cool Pope, The People's Pope, The Pope, Piss Unicycle,Darth Francis, Pope Trancis, Darth Peel Suit, Aliases: The Pope Francis, Fran, Frolo, The Pope Who Likes Poop, The Very Cool Pope, The People's Pope, The Pope, Piss Unicycle, Darth Francis, Pope Trancis, Darth Peel Suit, His Imperial and Royal Apostolic Majesty, Francis I, by the Grace of God and the Will of the Force, Emperor of the Holy Roman Empire and of the High Galactic Reach, Vicar of Jesus Christ and Successor of the Prince of the Apostles, Supreme Pontiff of the Universal Church, Patriarch of the West, Sovereign of the Papal States and the Kingdom of Jerusalem, Catholic King of Imperial Spain, of the Spains beyond the Seas, and of the New World, Archduke of Austria and Head of the House of Habsburg, Lord Protector of the Black Panther Party

John XXIII (includes human, mouse, and rat form names as all names would apply to him. Note, anything could literally be used as his name but this list is his confirmed and approved list)
Aliases: McCheese, McBraincell, McBrainula, McShareholder, McHumanity, McPoop, McDialogue, McReligiousLiberty, Chuck E. McFuck, McPoop, McBrain, McWeedula, Oreo, McFuckFace, McSagula, McLoser, McPepperwagon, McWoodEater, McMoron, Nothing, Pope John XXIII, Good Pope Chuckley, Pope St. Cheese XXIII, El Papa Bueno, The Pope Who Likes Cheese, Oreo, Nothing, Hey, Poop, J-dog, J-dawg

Flabe
Aliases: McYoogle, MCWalden, Waldorf, Woah, McWoah, McYaHee, McLafferty, Walden, McPinkerton, McUnionBuster, McTeeterTaw, Slack-Jawed McLafferty, Where's Waldo, McTahini, The Schlimey Little Schnaeiwl, McCataract, McCrinkley, McButterbuns, McButterfinger, McSawmill, McSawdust, Zlarvihan III, McBunkbed, McDungaree, McCorduroy, McDunkinDonuts, McCranklin, McGingerly, Chet, McBumberton, Greasy Flabe, Floogle, McZloobaha, McPinwheel, Pillhead McLafferty, McSnowsnailly, McMeatGrinder, McClomperShoe, McBumblebee, McSporran, McSpork, McClellan, McNeedlenose McClabe.

Docta Mista Hou
Aliases: Doctor Mister Houlihan, Casketios, Docta Hou, Craig O Hou, Pat' E' Os, Docta Mista Bankruptcy, Krabby O'Monday's

Kosh
Aliases: Kosh Kosh, John Paul II, JP2, Kosh TinyTowny, Jan Paweł

Eddie Kosh
Aliases: Eduardo, Eddieton, Spider McKosh, Edunator, Education

Pastor John
Aliases: John, The Good Flastor, Flastor John, Flastor Flohn, Flohn, Martin Luther, Pastor Buddha, Muhammed, Arius, Palamas, Nestorius, John Calvin, John of Leiden, The Winter King, King John II of Bohemia

King LGBT
Aliases: King Liberty Guns Beer Trump, King, The Big Man, Trump

Eitknee
Aliases: Shitknee, Gordon Shitknee, The Gordon Shitknee, Gordon Eitknee, The Gordon Eitknee

Uncle Free
Aliases: Uncle Poop, The Good Uncle, Free, Free Uncle, The Funny Old Robot Full Of Poop, Penis Head, Pope Freencis

Pooniella
Aliases: Pooniella Geedbeani, Pooniey Ole Rattlebones, Rattlebones, Rattlebeani, Pooniella Rattlebeani, Fish Mouth

Saint Hitler
Aliases: St. Hitler, Grampee, Pee, The Pee, Gramps, Adolf Gloopius Hitler

DD
Aliases: Detmold, Meeg Turg, Radioshack, Radioberg

Gary Smetanka
Aliases: Gare Bear, Tank, The Tank, Smetanski

JC Denton
Aliases: Kenneth Wildman, Jaecula, Jaecula C, JC, Justifiable Crimes Denton

AC Fenton
Aliases: A-C, Ottoman C, Big A Little C, Acula, Super A-C 

Blar
Aliases: Trashcan Carla, Blingo, Bluegill, Tranime Slop

Zejewgyatt
Aliases: Big Sabrosky, Zejew, HaHooHyatt

Chief Chuckachee
Aliases: The Chief, Evo Morales, McChee

Pope Maculon
Aliases: Maculon, Garbage Truck, The Pope Of Hell, MacuGarbage, Poopulon, Hell, Cigarette Butts, Ziggy, Zingly Zangly Zingulon, Siegfried, Ziggy Maculon, Benedict, Human Dignity Block, Benediction of the Mind, Benedict XVI, Pope von und zu Trauttsmandorf, Condescending, Frozen Custard

Deacon Schlick
Aliases: Flak, Brick. Stone Brick Fireplace, Zack, Joachim Andreas von Schlick, The Good Deacon, Clank