Pac-Man/WMG

The Ghosts are people trapped in purgatory, and Pac Man is the personification of their sins
See, purgatory is an endless series of mazes, in which you are forced to face your sins, manifested in physical form. Inky, Blinky, Pinky, and Clyde were humans once. They were drug addicts, who died while partying. Their sins manifested in a creature that mindlessly devours pills, just as they did in life. The only way for them to gain redemption is to face and destroy this creature. If they fail, and the creature wins, they will go to Hell.

Pac Man is a cannibal and the ghosts are the souls of those slain come to haunt him
Think about it, what does he mostly eat? Round yellow dots, occasionally larger yellow dots. What is Pac Man and the rest of the Pac Man family? A bunch of round yellow dots. Obviously Pac Man's major food sources are the infant members of his own species. The ghosts freak out when he eats the larger dot because they can't really defeat Pac Man themselves, they can merely possess him to hold him still and then possess the larger dot - the older juvenile- to kill him. When he eats the juveniles he robs them of their only hope to save the children and they wallow in blue wailing despair.

Inky, Blinky, and Pinky are all working for Clyde (possibly clones) to take down the Pac-Family.
He and his Quirky Miniboss Trio have been trusted with the job of slaying the monsters who keep destroying their world. They are the only people both powerful and willing enough to risk their lives fighting a monster that can permanently kill them as long as it has eaten a powerup first.
 * To be fair, Clyde was the leader in the non-canon Hanna-Barbera cartoon. But then again, they switched up thier personalities (for instance, Blinky was a stuttering coward.)
 * What...? Pac-Man CAN'T permanently kill the ghosts...

Pac-Man is Gluttony and the ghosts are EVA s.
Evas 0-3 have to fight off what Gluttony became after eating his way through this side of the Gate.

The Ghost Witch of Nentor is Erwin's mother.
We were never told where Nentor is, were we?
 * I'm pretty sure it's somewhere near Berwyn...

The Hanna-Barbera cartoon is canon
I want this to be true for one reason and one reason only: To make Pinky and Sue two separate ghosts once and for all so they can stop changing Pinky from a boy to a girl and back again! ARRRRRGH!!! Also, Chomp Chomp made a cameo appearance in one of the Pac-Man World games as a Continuity Nod.
 * Pinky and Sue were separate ghosts in Ms. Pac-Man and in Pac-Mania; when are they the same? (Though I did skip most of the Pac-Man World series; maybe it's there)
 * Namco officially declared Pinky to be female in the Pac-Man World Series. She was never changed back to being male. She only looked androgynous (and was assumed to be male) in the other games due to hardware limitations. So zip it, they're separate and they always have been. If anything, Sue is related to Clyde (see below).

The ghosts are the lives you lost
Whenever you loose an extra (Ms/Jr/regular) Pac-Man, she/he dies and becomes one of the four ghosts. He then chases the guy/girl who replaces him in order to get revenge on the player who killed him. They must stay inside the maze until they fullfill their wish for revenge no matter how long it takes, afterwards, they will be replaced with the Pac-man they killed. The cycle never ends.

Pac Man and Ms. Pac Man were actually developed simultaneously
Ms. Pac Man was actually developed intentionally along with Pac Man in order to get double publicity for nearly identical games. Namco got GCC to create Ms. Pac Man not as an unofficial bootleg but as a legitimate Pac Man game. Thanks to their explanation, (that Ms. Pac Man was originally a bootleg), it doesn't look like a cheap marketing move on Namco's part, and GCC gets the credit of developing a Pac Man game.

Sue, Tim, and Cruise Elroy are part of Blinky and Clyde's multiple personality disorder
Clyde eventually split Sue off into her own self, then saw a ghost therapist to do away with Tim. Cruise Elroy is Blinky becoming overcome with rage at Pac-Man for one reason or another.
 * Alternatively, Cruise Elroy is Blinky becoming possessed by Satan.

Chain Chomps are from the same dimension as Pac Man
They both come from a dimension where everything is pie-shaped. But at some point, both Pac-Man and the Chain Chomps got pulled out of it and into the ones that they are in today.

Pac-Man takes place in hell and the ghosts are demons sent to punish him
Pac-Man delves deeper into the heart of hell, endlessly forced to eat food off the floor of cramped dark hallways that turn back on themselves while avoiding Satan's minions who endlessly return to torment him for his gluttony in life. In the sequel, his girlfriend sets out to find him and finds herself delving down the same dark path her lover embarked upon.

The ghosts are Pac-Man's inner demons, his fears and obsessions
He, naturally lacks the courage to face his inner demons, and when he tries, it destroys him utterly. One of the things they represent is his crippling drug addiction, as the only thing that gives him the courage to move forward with his life, however briefly, is Pills.

The ghosts are just trying to prevent Pac-Man from eating all the food in the maze they've been trapped in.
However, the food is a magical artifact that, if all is eaten by the same person, it warps you back a few minutes and slowly inspires rage in all people nearby who didn't eat any.

The ghosts are hallucinations Pac-Man regularly experiences of people who tried to help him with his eating problem but that angrily gave up on him.
He perceives them as chasing him because he never even admitted he had a problem, so he views them as antagonists. When the hallucinations "catch up to him," he freaks out and collapses, sometimes never waking up.

The Real Life Story
Pac-Man the Ghost Hunter is exploring a haunted house. He finds four ghosts. He looks for flashlights (Power Pills) in the house to take them down. The pellets are actually batteries. What he doesn't know is he's actually just trying to delay them long enough to wait for help.

The ghosts are a Five-Man Band.

 * Clyde is The Hero
 * Inky is The Lancer
 * Kinky is obviously The Smart Guy
 * Blinky is The Big Guy
 * Pinky is The Chick

The ghosts are the Cult of Skaro
Rule of Funny comes into play here, but think about it: the Ghost Pen = the Void Sphere; Blinky = Sec, Pinky = Jast, Inky = Thay, and Clyde = Caan. Other than that, it's just funny.

The game is an allegory for a hopeless guerrilla war
Pac-Man represents a guerrilla army that's constantly on the move trying to avoid soldiers/agents belonging to a much larger foreign military force. The power pellets represent weapons sent in from outside sources sympathetic to the guerrillas. For a while, the guerrillas will gain an advantage, but eventually they'll run out of ammunition and will have to wait for the next resupply. Unfortunately, unless the guerrillas can somehow find a way to stop their invaders from sending in reinforcements, they're doomed to fight until they ultimately lose against the sheer numbers of the invaders.