Optimus Prime Pepsi Thirst Convoy
Hey, remember that time that Optimus Prime got really drunk and signed that sponsorship deal with Pepsi...? Yeah, neither did he. Until the lawyers came to make him follow through on his end of the deal. The success of Transformers when they were first launched led to various "variant" versions of familiar toys - You could mail in cookie coupons to get a Jazz toy, for example, who was made much more acceptable to parent-conscious corporations by removing the Martini logos from his doors (This Prime, however, is much more recent; he's a Japanese toy from 2005, released in America in 2007). Us, we're still waiting on a Sony-branded Soundwave.

Lucky Draw Convoy
This ultra-rare - Reportedly, only 10 ever produced - Optimus Prime was the result of a contest to find a new color scheme for the Autobots' leader. Surprisingly, this actually won. Can you imagine what the others must've been like? The Lucky Draw Transformers - almost all of which were prizes in contests, hence the name - were mostly repainted versions of widely-available toys, released for the most part in Japan, and widely sought after by American collectors. It may help if you're color blind, of course.

Trainbot Raiden
Primus bless whoever thought that there was some dynamic potential in making a train turn into a giant robot, considering how dull modern trains look - well, unless they're Astrotrain - but the wonderfully-named Trainbot Raiden was six trains that combined together to make one giant robot, Voltron-style. Released in Japan in 1987, who wouldn't want one of these?

The Blue Bluestreak
No, it's not a particularly redundant-sounding Marvel superhero from the 1960s, but instead a version of the Bluestreak toy who is... well, blue. The generally-released toy was actually painted silver - and later releases of the toy had the character renamed Silverstreak - but because the original catalog featured a blue version (and the painting of the robot on the toy packaging, for that matter) was colored blue, an urban myth was born. Are there real Blue Bluestreaks? Potentially - but there are those who'll refuse to believe it.

The Red Slag
Much like Bluestreak, this is a differently-colored version from the toy that a generation knew and loved, but there's one significant difference: There's photographic proof that this one existed. Just like the Blue Bluestreak, this toy matches his box art coloring, but anyone in the US looking for one would have to look north - This was a Canadian-only release, for some unknown reason.

Fortress Maximus/Grand Maximus
Fortress Maximus - or Fort Max to his friends - was only the largest Transformer ever, but at the time, the most expensive. But did that matter to its intended audience? Of course not! Released towards the end of the line's popularity in the US, and with a detachable head (thanks to the still-confusing Headmasters gimmick), the toy has become hard to find in America, but not as hard as Grand Maximus, a repainted version of the toy sold in Japan as Fortress' more colorful brother, kind of like Ultra Magnus in reverse.

Action Masters Elite
Let's get this out the way right now: The Action Masters subset of the Transformers line? A completely bad idea. For those of you who don't remember the Action Masters, this is their gimmick: They were Transformers that didn't transform. You'd think that someone, somewhere at Hasbro might have realized that that wasn't the greatest gimmick for a toyline called "Transformers," and that might have been the reason behind the Action Master Elite line... who were Action Masters who did transform... or, to put it another way, Transformers. Sadly, the Action Masters were enough of a bad idea that they temporarily killed the franchise in the US, leading to the Elite toys never being released over here. So, if you find one of these cheap, treasure it... while also hating everything it stood for.

G1 Jetfire
To anyone who followed the Transformers comic book in the '80s, Jetfire had a special place in our hearts because he was created by Buster after Optimus left the creation matrix in his head. But even for non-comic nerds, Jetfire was special - For one thing, he wasn't really a Transformer, but a licensed Macross toy added to the line to meet demand for new characters by a panicked Hasbro, and for another, he had three forms, not just two... but the licensing deal didn't last, and so neither did the toy despite how cool it seemed. The one to look for is the initial Transformers release, complete with Macross markings as well as Autobot insignia.

The Dinobot Tapes
Yes, there were Autobot cassette Transformers. Even stranger, these Japan-only toys were also Dinobots and Combiners. Why did no-one ever tell me about these when I was a kid? I would've killed for these - and also for Blaster, the Autobot tape player that quickly became my Must Have toy when I learned of its existence as a kid (Note to Hasbro: if you have one just lying around, I can be bribed. Just saying).

Generation 1 Unicron
Called "the holy grail" for Transformers obsessives - as well as one of the ugliest toys never made by fans - this prototype for an unreleased toy of the villain from the 1986 animated movie tries its hardest to make a ball with limbs and a head look threatening, but still fails. Maybe if he'd actually have been able to sound like Orson Welles, it would've been better, but even then, I'm sure that would've just led to more fat jokes.

Research and additional reporting by Sarah Hope Williams.

Now, we know that this list is going to upset more than a few of you (Especially if you disliked the three Star Wars prequels), but we're not ranking these killer robots in order of awesome - Because then you would have seen IG-88 and KARR, amongst others - nor even in order of evil, but literally in terms of estimated kill-rate. Which robot has killed the most living things? That's all we're interested in.

So, get started with the countdown, and feel free to dispute our choices in the comments. Just don't send a robot after us, to change our minds.

Who else have we missed? Tell all here.

Next: See who didn't make the list.

Next: Science Fiction's Most Killhappy Robots!

Next: Planet-Eating Robots!

Next: Genocidal Robots With A Plan!

Next: Ineffectual-But-Deadly Droids!

Next: Time-Traveling Murder Machines!

Next: Eco-Friendly Killbots!

Next: Mutant-Hunting Robots!

Next: The Self-repairing Murderbot!

Next: Robot Warriors!

#3: The Doomsday Machine: Okay, so this danger from a 1967 episode of Star Trek isn't exactly a person as much as a giant machine that consumes planets to fuel its own destructive rampage, but dude! Consuming planets! One of Trek's better fear-of-technology menaces, this particular planet eater gains extra points for destroying an entire starship and, according to a novel written more than twenty years later by Peter David, having been created to destroy Next Generation villains the Borg by a whole race of Whoopi Goldbergs.

#2: Unicron: Only one man could properly portray the voice of a planet that transforms into a robot that eats planets - self-loathing much? - and that man had to be Orson Welles, ending his career with a suitable bookend to his Citizen Kane start with his last ever role in 1986's Transformers: The Movie. If you were twelve years old when the movie came out then Unicron was possibly the greatest evil Transformer ever, mostly because of the fact that he made shitty old Megatron into the Leonard Nimoy-voiced Galvatron. More proof that he was awesome came in the fact that it took toymakers seventeen years to come up with a toy that measured up to fans' expectations. But even Unicron is just a pale imitation of...

#1: Galactus: Easily the biggest and best of sci-fi's planet eaters, Galactus' victory comes from the fact that - unlike Unicron or the Doomsday Machine - he isn't a robot but an honest-to-goodness force of nature. The sole survivor of a pre-Big Bang universe, the Fantastic Four's largest enemy may have been killed more than once in various stories since his 1966 first appearance (including being eaten by superhuman zombies in parallel world comedy Marvel Zombies), but nothing can keep a large purple-bucket-headed cosmic entity down for that long, even one given to pretentious monologues about how hungry he is.

Others may come and try to steal Galactus' crown but, really, who even remembers DC Comics' Imperiex, even if he does call himself "the devourer of galaxies"? Exactly. Created by comic greats Stan Lee and Jack Kirby, Galactus is proof that sometimes, the biggest threat really is the best. But what about the rest of you? Is there another villain of planetary appetite that should be added to the list?

The Doomsday Machine [Star Trek.com]
Unicron [Teletraan 1]
Galactus [Marvel Directory.com]