BEST:

Spot, Data's Orange Tabby Cat from Star Trek: The Next Generation
Who: Data's number 1 friend that didn't wear a Devo-esque visor on his face.
Why he's awesome: He's probably one of the only cats in the universe that has an infinitely advanced AI at his beck and call.
Bonus points: Anything that pisses Riker off is a big plus in my book.

Willis the Bouncer from Robert Heinlein's Red Planet
Who: A sound mimicking furry ball that every kid should have as a friend.
Why he's awesome: In a 1960's era future, when a dog just won't cut it, the only way to really impress the kids at school is with an alien that doubles as a soccer ball. And here's a clip from the Fox miniseries adaptation.

R2D2, Star Wars
Who: The yin to C3PO's (annoying) yang that brings logic and light to any situation through a series of flickering lights and bleeps.
Why he's awesome: He's a moving trashcan that manages to be more likeable than most of the Star Wars palz extended cast.

Porthos, Captain Archer's Beagle from Enterprise
Who: Easily one of the more tolerable characters on Enterprise. Mostly because he didn't talk.
Why he's awesome: He's a beagle! How can beagles not be cute? Also, I feel like after the unfortunate Scotty related transporter incident, he deserves a nice memorial.

Ampersand, Y the Last man
Who: The world's ending, every man is dead, you're an aspiring escape artist pining away for your lost girlfriend and you're all alone. What do you do? Have crazy monkey antics with your favorite jungle friend with a punctuation mark as a name.
Why he's awesome: Not to spoil too much, but he may or may not be humanity's key to getting the XY's back in action.

Lockjaw
Who: Marvel's own alien bulldog and member of the non-human branch of the Avengers.
Why he's awesome: He's super strong, can eat anything and once latched onto the Thing.

Dog the Robot from Half Life 2
Who: Alyx Vance's No.1 go to robotic buddy who helps when your path is blocked by other dimensional beings or just wants to play fetch with your grav gun.
Why he's awesome: He's a giant robot with the personality of a dog. Do you need more?

Pen Pen, from Neon Genesis Evangelion
Who: A genetically altered super smart penguin that lives with Misato Katsuragi during the Angel apocalypse.
Why he's awesome: While the series has moments of intense despair and darkness, you can always count on jerky, anime humor involving naked people and penguins to brighten your day.

K-9 from Doctor Who
Who: Dr Who's multi-generational robotic canine companion.
Why he's awesome: He's gotten a series of spinoff stories and was even parodied on South Park.

Nibbler from Futurama
Who: Nibbler is part of an ancient race of Nibblonians who protect the universe from giant glowing brains that make everyone stupid. Er, Stupid-er.
Why he's awesome: He can eat about 1,000 times his body mass to, uh, produce dark matter.

Gaspode, from Terry Prachett's Discworld series
Who: A talking dog with human intelligence that attempts to bring "Hollywood" to Discworld.
Why he's awesome: He's an endless source of snarky remarks and regularly uses his speech to manipulate humans when he needs food.

CJ-7
Who: A puff ball with a body that guaranteed to produce family friendly fun times.
Why he's awesome: CJ-7 can help you repair torn relationships with certain parental figures and bring people back from the dead.

Einstein, Doc Brown's dog from Back to the Future
Who: You might be under the impression that a certain Family Ties alum might be the Doc's best time traveling friend in this series, but you'd be wrong. This adorable little terrier follows Doc whenever her goes.
Why he's awesome: As long as you ignore the craptacular animated television series, Einstein is always cute, helpful and never obnoxious.

Ein, Cowboy Bebop
Who: A super brained corgie that gets stranded on the Bebop.
Why he's awesome: Although they never really get into it in the series, Ein is a "data dog" that possesses super intelligence that allows him to answer phones and steer cars.

Bubastis, Ozymandias' lynx from Watchmen
Who: When you're a super genius David Bowie impersonator with the world at your fingertips what do you do next? You create a genetically engineered psychedelic colored lynx as a companion.
Why he's awesome: He takes one for the team for the sake of furthering an evil plan for his master.

Gizmo, Gremlins
Who: The main furry faced protagonist of the Gremlins series.
Why he's awesome: While I'm pretty much a fan of all the gremlins, I can't deny the greatness that is Gizmo channeling his inner Rambo.

Seymour from Futurama
Who: Seymour is a part of one of the most tear jerking episodes of Futurama involving Fry recounting the story of the most loyal dog that ever lived.
Why he's awesome: Did you see the last scene? He's the most loyal dog that ever lived! Also, we can rest easy knowing that alternate timeline Fry gave Seymour a great life.

Bronx from Gargoyles
Who: Bronx is the dog version of the Manhattan gargoyle clan. During the whole series you only see one other gargoyle beast, but unlike Budeka, Bronx gets a whole episode devoted to him befriending an Amish kid.
Why he's awesome: Gargoyles are already pretty high on the cool supercreatures scale, but add a dog personality to the mix, and you've got gold.

Roach from WALL-E
Who: They weren't lying when they said that after the world ended there would be nothing left but cockroaches. Fortunately, the end of the world also gave them charming personalities!
Why he's awesome: Making me want a roach as a pet is an epic win in my book.

Kevin and Dug from Up
Who: Kevin is a rare, brilliantly colored giant bird that Carl and Russell accidentally find in Paradise Falls. Dug is sweet golden retriever with a collar that allows him to talk.
Why they're awesome: It takes a lot to make slapstick giant birds funny, but Pixar does a magnificent job. And Dug? He's exactly what I imagine an actual talking dog to sound like. SQUIRREL!

WORST:

Tribbles from Star Trek
Who: Fuzzy, purring little meat pets that take over the original Enterprise.
Why they suck: Pets rocks were bad enough, why would they think that a massively multiplying furry pet rock would be better?

ALF
Who: Alien puppet that takes over a really lame sitcom in the 80's. If ever you want to torture someone without the use of waterboarding, show them and episode of ALF… or Small Wonder.
Why he sucks: Look me straight in the eye and tell me you didn't scream in horror when you saw that clip.

Snarf, Thundercats
Who: A fat alien cat that ends every sentence with an annoying "snarf!" sound.
Why he sucks: Is he a lizard or a cat? I'm going to go with meth induced demonic lovechild.

Teddy from A.I.
Who: An animatronic intelligent Teddy Rucksbin from the future that accompanies David in a search for the Blue Fairy.
Why he sucks: Ok, now I understand that some people might take issue with Teddy's position on the worst list but he's a toy that's alive. That's pretty much the worst nightmare of most 8-year-old kids. And me.

Slimer from Ghostbusters
Who: A green ghost that terrorizes the Ghostbusters team by covering everything in slime.
Why he sucks: For those of us born in the mid 80's and watched the Ghostbusters cartoon first, we expected to see cool ghost antics when we finally saw the movie. Instead, we were greeted with a grotesque blob that was pretty evil.

Div-x from Penny Arcade
Who: You might remember the Sony Dix-X player, an ahead of its time technical marvel.
Why he sucks: According to Penny Arcade Comics, he's a foul-mouthed drunk that's teetering on the edge of killing us all.

Pets from Children of Men
Who: When the world's gone infertile, people turn to animals to provide comfort in the end of humanity.
Why they suck: I have nothing against the animals in Children of Men, personally, but seeing all the dogs, cats and birds cluttering people's homes can be an ominous image.

Selacious Crumb from Star Wars
Who: He's a little fox-lizard thing that hangs out with Jabba the Hut and laughs at all his lame jokes.
Why he sucks: Everybody hates the skinny jerk in the corner with the stupid laugh.

Gleek from Superfriends
Who: The alien monkey pet of the Wondertwins.
Why he sucks: Usually if he was featured in Superfriends, you could count on him popping out to end the episode on a lame joke.

Independence Day Dog from Independence Day
Who: If you're like me then you probably laughed at the idea of a ball of flame chasing a golden retriever down a tunnel.
Why he sucks: Was it really necessary to have a slow motion explosion behind a dog? And wouldn't all that heat ultimately cook them all in that storage locker?
Then Again:...he's immune to explosions. And that's pretty cool. Dodging fire like that, he's like a canine Neo. Maybe he should have been best?

Space Buddies
Why they suck: I'll just point you in the direction of this.

Queequeg, X-files
Who: A Pomeranian adopted by Dana Scully and eaten shortly after by the legendary Big Blue.
Why he sucks: He was found snacking on his previous owner.

Krypto
Who: Superman's dog. Enough said.
Why he sucks: I hate pet versions of superheroes. Also, why does he need a cape?

Muffit from the original Battlestar Gallactica
Who: Caprica used to have a variety of tracker dogs but sadly, none of them survived the Cylon attack. Instead a group robotic dogs are created to replace them.
Why he sucks: Is he an ewok? A fuzzy, metallic gremlin on meth? You decide.

MAD Cat from Inspector Gadget
Who: Dr. Claw's chortling fat feline.
Why he sucks: He's the quintessential evil cat meant to taunt the hero. Plus Dr. Claw regularly beat the crap out of him and he seemed to be ok with that.

Frank the Dog from Men in Black
Who: An alien stool pigeon using the guise of a small pug.
Why he sucks: He made me remember "Who Let the Dogs Out" existed.

Gir, Invader Zim
Who: Invader Zim's mentally disturbed robot helper that was given to him as either a joke or sabotage. Probably both.
Why he sucks: Yeah, yeah Gir is really cute, but he's amoral, evil and would gladly watch you die a fiery death while bursting into a fit of giggles.

Astro, The Jetsons
Who: The Scooby Doo knockoff of the 21st century.
Why he sucks: It might have worked with the Scooby Gang, but there's only room for one charismatic dog with a speech impediment ‘round these parts.

Lamar, Half Life 2
Who: The neutered headcrab that resides in Dr. Isaac Kleiner's laboratory.
Why he sucks: Crabs are rarely a good thing. Head crabs are a double whammy of bad.

Joshua from Dark Angel
Who: A transgenic dog-man with an affinity for painting and crappy comedic timing.
Why he sucks: There was only one good thing that came out of season two of Dark Angel and that rhymes with Smensen Shackles.

Honorable Mention: Blarp from the Lost in Space remake.

Usually when we throw together a list of "the best this" or "the definitive that," we're willing to concede that we might have missed something. But this time, we're screeching and flinging our own feces with the total confidence that we have covered all of the space monkeys in history. Mostly thanks to the obsessive-compulsive maniacs at Monkey Conspiracy, who compiled an exhaustive list of monkey films. Plus Mr. Monkey's List of Famous Monkeys. Top image from Adrian Platts.

First of all, of course, there are the Planet of the Apes movies, which are almost their own genre. (We won't even get into the thorny question of whether apes are monkeys.) it's the distant future, except in the Burton version where maybe it's an alternate Earth, and apes have taken over, and humans can't talk. It's all part of some bizarro analogy for race relations in America.

Space Chimps, coming this summer, is an animated movie about the grandson of the first chimp in space. Ham III gets blasted into space by an unscrupulous senator. Then, somehow, he gets zapped to a faraway star system, where he has to help overthrow the evil ruler of another inhabited planet. Good thing two other smart, resourceful chimps are on board his spaceship.

Captain Simian & The Space Monkeys. An animated show from the mid-1990s, and yet another story about astronaut monkeys. This time, a monkey-naut in the 1960s gets lost in the outer reaches of space, only to get picked up by a race so advanced, nobody can pronounce their name. The monkey gets an upgrade, including enhanced intelligence and high tech, and recruits a squad of other monkeys to fight a villain who's half-human, half-black hole (and who wants to destroy the universe.)

Lost In Space. The TV show and the movie had many important differences, but one central element remained constant: Penny's space monkey. In the TV show, she befriends a weird alien monkey with long ears named Debbie, or Bloop, after the funny noise she makes. In the movie, the monkey's named Blarp, and instead of being a real chimpanzee with a funny hat, she's CGI mixed with animatronic:

Star Trek: Voyager. In one of the most memorable episodes of Voyager, "Resolutions," Captain Janeway and Chakotay get bitten by an insect, so they can never leave a particular planet. Voyager has to go warping off without them, leaving Janeway and Chakotay to put on funny vests and take up gardening and pandering to J/C shippers. But there's a complication: Janeway meets a cute-ass monkey, who threatens to steal her affections away from Chakotay. Which one will she choose? Luckily, Voyager comes back with a miracle cure before Janeway has to decide. That was close!

2001: A Space Odyssey. There are some apes tossing a bone around on a lazy Sunday, and then a big obelisk/monolith thingy shows up. I don't think the apes ever get into space in this film, but space comes to them. So I'm including it.

Monkeys In Space. A twice-weekly webcomic about a group of monkeys zipping around the galaxy and trying to wipe out the remnants of the human race. And score some bananas:

Moon Pilot. Another movie about chimp astronauts, this 1962 Disney comedy features a space chimp who makes contact with a race of telepathic aliens, who just happen to look like hawt babes. No human astronaut wants to follow in the path of the alien-crazed chimp, until he sticks a fork in a young trainee's ass at a dinner party, prompting the man to volunteer by mistake.

The Right Stuff. NASA wants to send monkeys up into space before it sends up any trained astronauts, prompting the classic line: "The issue here ain't pussy, it's monkey." But why can't it be both?

Robot Monster. An alien invader, looking suspiciously like a man in a gorilla suit with a diving helmet on his head, manages to kill everyone on Earth... except for six people. The film was such a huge disaster, the director reportedly attempted suicide (unsuccessfully.) Here's a clip:

Rocket Man. A spaceship full of humans blasts off into deep space, with the humans in suspended animation. But the ship's resident chimp (you have to have one, it's regulations) accidentally wakes one of the humans up, and he has to spend months entertaining himself while the other humans sleep. Good thing he's got a chimp to keep him company.

Space Ghost. In the original 1967 cartoon, Space Ghost had twin sidekicks, Jan and Jace. (Not unlike the wonder twins in Superfriends.) And Jan and Jace had a pet monkey, Blip. Similarly, the Wonder Twins had their pet blue monkey, Gleek.

The Existential Adventures of ASTRO-CHIMP, First Monkey In Space. An animated program on the Sci Fi Channel, this is yet another astronaut chimp show, which supposedly is incredibly boring and pointless despite its cool name.

The Monkey In The Rocket by Jean Bethell. A children's book about monkeys in the space program. Sample lines: "Sam and Bam are Monkeys. They are very special monkeys that live in a very special place... at the Blue Sky Rocket Base." Sam is the bravest little monkey, who volunteers (sort of) for a one-way trip to the farthest reaches of the universe... and oxygen starvation!

The Scary/Angry Monkey Show. On Invader Zim, Zim's robot servant Gir is obsessed with a TV show that's either called Scary Monkey or Angry Monkey. It seems to consist of a monkey, sometimes wearing a band-aid, looking somewhat pissy or freaky. He's obviously in outer space, or why would he be in such cramped quarters?

Dexter's Laboratory. The monkey Simion gets shot into space and becomes hyper-intelligent (of course) and then becomes a supervillain. His dastardly scheme: Invade Earth to get revenge on all the humans who helped make him the megalomaniac he is.

Monkey Business by J. Otto Sebold and Vivian Walsh. The first monkey in space, conveniently called Space Monkey, comes back to Earth and starts a business to capitalize on his fame: he builds a supercomputer that turns out objects that look like cubist cupcakes. Nobody's sure what they are, but they're tremendously popular. Then it turns out if you point a TV remote control at the objects, they open up into tiny apartments.

Apparently he's been fairly busy, having served as a writer and performer on Sabrina, The Teeange Witch and the brilliant but canceled Invader Zim on Nickelodeon. But fear not, because he'll be rejoining MST3K cast members Joel Hogsdon, Trace "Crow " Beaulieu, J. Elvis "Tom Servo" Weinstein, and Mary Jo Pehl for "Cinematic Titanic," which sounds like a lot like MST3K Version 2.0, minus the robots and the mads.