30 Rock/WMG

Dr. Drew Baird is Don Draper's illegitimate son
Remember that Liz's mom worked for Sterling Cooper in the 60s, so we know Mad Men and 30 Rock share a common universe. And we know from St. Valentine's Day that Drew's mother had him out of wedlock in her teens or early 20s. And he was probably born sometime in the 60s, and he looks just like Don Draper. It all adds up to Drew Baird being Don Draper's bastard son.

Past Pete really WAS coming to kill future Pete.
Tracy found out about while running through the studio, but nobody believed him because of his craziness. Fortunately, Past Pete failed and went back to the past. That's why Pete never wore the wig again. He never had one.

The show is real--we are the Good End Alternate Universe!
Think about it! Liz wants to have a good boyfriend and possibly get married and have kids! Tina Fey is really able to become an accomplished writer who has also acted in various films and shows unlike her real-life counterpart. Tracy and Tracy both come from slightly sad backgrounds, but then again, both made it on top--Morgan did do some serious films, though. Jenna's actually trying to deny the fact that she's getting old, but now, Jane's become a dignified model and actress at 37! But Kenneth might be a transdimensional constant.

Jack is right about Kenneth.
Kenneth is Obfuscating Stupidity in an attempt to take over the whole company, possibly the world. Everything he's done on the show is all part of a complex master plan.
 * His page job at the Olympics was a major step. By now, he rules half of China.
 * Alternatively, when the NBC/ Comcast Kabletown deal goes through it'll be discovered that between the NBC stock in his 401(k), some shares in one of Kabletown's predecessor companies that his grandfather invested in in The Fifties when one-man cable operations in rural areas were common and an interest in Sheinhardt we didn't know about, Kenneth has a controlling interest in the new company.
 * His grandfather...right.
 * Interestingly, in season 1 Jack theorized that Kenneth would end up running the company in 5 years. It's now season 5, and now that Kabletown owns NBC, it's being run by a guy who Jack explicitly compares to Kenneth in terms out outlook and personality.

Liz has Asperger's syndrome.
She's a geek, and Jack says that she's "socially retarded", which seems to be true. That defines Asperger syndrome right there, doesn't it?
 * No, it doesn't. She doesn't seem to have many other symptoms.
 * Agreed. You clearly haven't met anyone with a serious case of Aspergers. Most real people with serious cases of Asperger syndrome are more like Kenneth than Liz. That is, assuming the above theory about him isn't true.
 * Liz is way too social to have Aspergers. Liz was a part of Second City back in the day. A person with Aspergers would not be able to go and perform in front of a bunch of people like that.
 * To be fair, Dan Aykroyd has Aspergers, and he was in Second City. But I agree, Liz shows no real sign of having it.
 * This Asperger's troper goes to a drama class and has no problem performing on stage, but other than that I agree Liz dosen't really seem to be Aspergers.
 * Also, one of the symptoms many people on the Autistic spectrum have is the inability to deal with noise. Liz seems to have the normal reaction when dealing with noise.
 * Asperger Syndrome is part of the Autistic spectrum. Liz may have some autistic atributes but probably not enough to be offically diagnosed.

Liz is the classic geeky-social-misfit-turned-comedian.
She started making people laugh with her not at her, probably as a child. She got good enough at it to do it professionally in a "glamorous" network TV setting. And then the Peter Principle kicked in, and she wound up in a position that's as much Human Resources as it is comedy writing.

Liz is the grown-up version of Carly.
This does run into serious continuity issues - 30 Rock doesn't seem to be Twenty Minutes (or years) into the Future, and iCarly by definition can't be set in The Eighties... so there is a Time Paradox in there somewhere.
 * There is a very plausible WMG that Carly is a Haruhi, so that might provide an alternative explanation.

Kenneth is immortal.
As mentioned elsewhere, he has apparently owned a pet bird for over 60 years.
 * In another episode we flashback to people dancing "The Microwave" in The Fifties -- Kenneth is one of the dancers.
 * There was also a deleted scene from "Mamma Mia" in which a World War Two veteran recognizes him as one of his war buddies.
 * And when he has to replace Donaghy's pants: "You know that woman in accounting who thinks you're her dead husband from the war?"
 * When he started working at NBC, Shirley Temple was eight - that's 1936/37.
 * But, most chillingly, someone asks him if he wants to be a page forever, and he mishears and replies (in a very disturbing tone for him) "Who says I have been alive forever?". Either he simply looks very good for his age, or our favorite NBC page is some sort of Humanoid Abomination.
 * In the closing tag of 100 Kenneth's hand pops out of his grave, giving a thumbs up. It also reveals his birth year as 1781.
 * See http://www.youtube.com/watch?v=jLStS6bSWeg

Kenneth is the Wandering Jew.
His devout Christianity is due to actually witnessing the life of Jesus millennia ago.

Kenneth is the Spirit of America.
We know that Kenneth has lived through all of the 20th Century at least, as noted above. His life has followed the trajectory of American culture: born in the backwoods, raised by a small, (putatively) nuclear family, educated at Bible College... then was seen in the swing dance halls of the '20s, served with the Greatest Generation in World War II, and finally moved to the Big City and joined the world of television, where America's heart now lies. His crazy can-do optimism and ability to do absolutely anything despite appearing utterly incompetent, only serve to underscore his quintessential Americanosity against the backdrop of a modern business and cultural environment that sometimes forgets the values upon which this great nation was founded.

Kenneth is related to Forrest Gump.
The more you think about it, the more it makes sense.

Kenneth is related to Jennifer Rogers.
She touched his face and was instantly repulsed after touching her own for reference. It wouldn't be the first time the cousin card was played on the show.

The Generalissimo in Elise's grandmother's soap opera is played by Jack's evil twin brother.
He looks exactly the same. And just look at the other Donaghys that appeared on the show; Evil Twin Separated at Birth seems almost mundane.

OR

The Generalissimo in Elise's grandmother's soap opera is played by Jack's good twin brother.
Think about it.

Kenneth is a Highland Immortal.
He had the same bird for sixty years. But he looks young.
 * Naturally, his bird is also a Highland Immortal.
 * No, some birds just live that long. Macaws live well over 90 years in captivity, for example. And didn't it die of pesticide poisoning?
 * And the whole 'innocent farmboy' thing is just an act so he can get the jump on other immortals.

Kenneth drank from the spring in Tuck Everlasting.
He is taking it much better than the Tucks did.

Kenneth brought back an Eldritch Abomination or an Artifact of Doom when he came back from the dead.
This, as with many things regarding Kenneth, does not bode well for mankind.

Jack Donaghy represents the mentality of Real Life NBC executives exactly.
So, if anyone still cares about NBC, then they ought to watch this show.

Kenneth drank from the Fountain of Youth in Pirates of the Caribbean.
See, about sixty years ago, Jack Sparrow had another curse on him that made him avoid the sea. He was exploring the Appalachians when he fell, hit his head, and was adopted by a nice family that washed his hair for the first time in his life (turns out he's blonde) and gave him a pet bird. If they had tried to teach him that rum was the devil's drink rather than coffee the devil's temperature, then he'd have been out of there like a shot.

30 Rock isn't a parody -- it's Tina Fey's and Tracy Morgan's anecdotes about their time at SNL with people's names changed to protect the innocent.
Yes, that means there really is an immortal NBC page out there.

Tracy Jordan isn't crazy; he just acts that way to get attention.
It's confirmed that some of Tracy's weirdness is an image: ""If I'm normal, I'm boring. If I'm boring I'm poor and poor people can't afford to pay back the $75,000 in cash they owe Quincy Jones!""

Tina Fey and Liz Lemon and Kenneth are Tropers.
It would be very surprising if they weren't.

There is going to be a Liz Lemon/Jenna Maroney plotline any day now.
Recall "Season 4" (the episode), where Jenna remarks that her options are to become a country music star or enter a lesbian relationship. She seems to be dropping the country act lately, and during "Into the Crevasse" she was very interested in the Liz/Jenna porno going on...
 * Confirmed in the same season's finale.

Kenneth's mom's friend Ron is Ron Swanson from Parks and Recreation.
We, after all, don't know anything about Kenneth's mother. As long as she's a pretty, dark-haired woman named "Tammy", it fits. She doesn't even have to be the Tammy played by Megan Mullally.

Kenneth is the human embodiment of the human conscience.
Liz, Jack, Tracy, and Jenna are all selfish people in their own way and Kenneth's goal is to set them in the write direction. Kenneth can never affect the outcome events but can influence others.
 * Liz can tend to be arrogant and elitist. She also occasionally becomes very whiny about her problems. Kenneth is there to remind her that there are people who have it a lot worse off than her and she should count her blessings.
 * Jack frequently is faced with moral dilemmas and Kenneth is always around to remind him of his guilt and to make the right decisions.
 * Tracy often participates in various crazy schemes and Kenneth is usually around to remind him of how his actions have consequences on others and attempts to ground him in real life scenarios.
 * Jenna is a self-centered individual and Kenneth has on numerous occasions attempted to allow her to become selfless.

TGS was cancelled three years ago, and no-one noticed.
Given that they spend all their time solving various wacky personal problems and dealing with Tracy and Jenna's craziness, they've simply forgotten all about writing, rehearsing and performing sketches.

The Live episode was a depiction of how Jack sees the world while sober.
He spent the whole episode sober for the first time in ten years. As soon as he took a drink, the show went back to normal.
 * When he was sober he was apparently able to see into Liz's flashbacks (and note that she imagines herself as looking different). Interesting, considering how clever and focused he can be when drunk. Sobriety just takes his natural brainpower Up to Eleven, giving him literal superpowers. We'd better hope he stays on the stuff. A psychic Jack Donaghy could take over the world!

== By the finale of Season 5 (or less likely, during the first episode of Season 6), Kenneth will have either taken over NBC or Kabletown by some strange confluence of incidents, historical or otherwise, or doomed everyone one way or another. == Early in Season 1, Jack said that in five years, they would all be ruled over by Kenneth or die by his hands. The "die by his hands" thing is unlikely, even if it's the Series Finale, but Kenneth-from-pre-industrial-Stone-Mountain ruling over NBC (even without exercising any power) would be even more comically nauseating for Jack than Kabletown alone.
 * Seeing how in Que sorpresa!, . This may actually happen.
 * Jossed as of "The Ballad of Kenneth Parcell." He's instead gone into a downward spiral.

Donaghy Estates Champagne is like Nia's Cooking from Tengen Toppa Gurren Lagann
Everyone who drinks it hates it and spits it out, but Tracy Jordan drinks several glasses while sitting in a meeting with Jack during "The Source Awards". Just like Nia's cooking is directly related to how much spiral power each character possesses in Gurren Lagann, how much the characters like Donaghy Estates relates to how much spiral power they have, it's just that Tracy is the only one who has any.

Lutz is a zombie
It would explain all his health issues (extreme gas passing, him with his shirt off...) and it would explain his reaction to Liz saying "one unsolved crew member death".

Carmen Chao is one of Kenneth's race.
She has no discernible background and may or may not be able to speak every language. She's clearly their Richard Alpert.

Paul (Will Forte) is the same character that he was in "Black Tie," Tomas. This could work in one of two ways:
1. After meeting Jenna at the party, he became infatuated with her, leading him to change his name and his new lookalike persona.

2. Because Jenna was basically responsible for Prince Gerhardt's death, he swore revenge upon her and is using their relationship to get closer to her and take her down.
 * 2a. The above was the original plan, but he actually did fall in love with her along the way.

Kenneth is an Angel Unaware
This is why he hates to lie. It goes against his nature. Should he fall, humanity will have difficulties.
 * In 6.16 Jenna asks if she's a terrible person and Kenneth replies "only God and his angels can judge... so, yes."

Kenneth is the latest host to an immortal alien parasite.
The Parcells are an ordinary tribe of humans who have been inbred to homogeneity to suit the preferences of the alien parasite.

Kenneth is a Time Lord.
He may not be immortal, just a time traveler that can live for a very long time.
 * Kenneth has keepsakes that directly reference him just like the Doctor.
 * Kenneth makes many references that outdate his outward age appearance like the Doctor.
 * Donaghy's supernatural business sense foreshadowed Kenneth taking over the company in five years, and a man with similar personality to Kenneth is running Kabletown. Maybe Kenneth regenerates at some point to become the owner?
 * He strokes and kisses 30 Rockefeller Plaza like The Doctor strokes his TARDIS. Maybe 30 Rock is Kenneth's TARDIS?
 * Kenneth once referred to himself as "the elderly". The Doctor has done this on a number of different occasions, claiming he's "much older than he looks" or "an old man".
 * During a televised dance for "Do the Microwave" in the 50s, Kenneth himself can be spotted in the crowd. This is a common antic for a number of different incarnations of the Doctor.
 * In season one, Cerie mentions to Kenneth that she feels he "has an old soul", to which Kenneth makes a wacky anecdote about being the reincarnated soul of the town minister who died in a fire. Perhaps this minister didn't really "die"; he's just one of Kenneth's previous regenerations.
 * When Jenna puts strawberries into Kenneth's sandwich (he's allergic to strawberries), Kenneth blurts out "My real name is Dick Whitman!" while in shock. While it's unlikely that he is the same person in Mad Men, as that character has an established childhood/birth; perhaps one of Kenneth's other regenerations was called "Dick Whitman". In Doctor Who, the Doctor will sometimes make asynchronous statements from other regenerations when incapacitated; Kenneth may have been doing the same thing.
 * Seeing as the writers of this show are admitted ubernerds, it would be a safe guess that they are, at least, aware of TV Tropes and the running gag it has about wild mass guessing various characters in fiction are time lords. The writers may have actually written Kenneth to, at least, showcase time lord traits so they could get tropers to write about it here. If that is the case...well played, Lemon.
 * Kenneth has also implied that he doesn't sleep, but instead sits in the dark and patiently waits for daytime. The Doctor also does not appear to ever sleep.

The show is porn for geeks.
Just like the "Porn for women" concept, the entire show is designed to be "turn on" for geeks. Let's just count the damage: Liz has the body of Tina Fey, an interest in all sorts of geeky things, and while smart and creative, she is at the same time predictable, subservient and dependent.
 * They still haven't had the obligatory Felicia Day cameo for the show to be true geek porn.