Part 1: Terran
The Terran race is heavily built on the Alien and Starship Troopers movies on the one hand and, as has been argued extensively, on Warhammer 40 000.
The best example of this is the marine. The marine has borrowed from all three franchises. On the one hand they’re wearing power armor, the mainstay of 40k Space Marines and their name alludes strongly to the warriors of Mankind and the Emperor.
Starcraft Marine
Warhammer 40000 Space Marine
As you can tell Blizzard basically took much of the general look of the Space Marine. However, beyond aesthetics they have very little in common with Space Marines. Space Marines are one-man armies, there are only ten thousand or so against the whole of the galaxy. They are routinely described as fanatically dedicated, religious to the extreme and good at basically everything. Marines, however, are like this:
Terran Marine: (taking a beer out of the container for a nuclear bomb) Thank God for cold fusion!
Terran Marine: Hey, are we really gonna blow this place?
Terran Marine: Only if we see a Zerg!
Terran Marine: Yeah, I got your Zerg right here. Heh heh. (takes a swig of beer and gets impaled by a Hydralisk)
This entire cutscene is a homage to Alien if there ever was one (I’ll be going into the Zerg bit in the clip in a future installment). It shows very well how Terran marines are routinely described as hicks and backwater, much like the entirety of Terran society. They’re lightyears from their 40k namesakes. They're prey to the Zerg and never shown as competent, brave or intelligent.
Similarly, the SCV look with their exosuit is suspiciously similar to the one Riley dons in Alien:
Starcraft SCV
Ripley's version is more scaled-down but the arms in particular suggests a clear inspiration.
The movie - moreso than the book - Starship Troopers is omnipresent as an inspiration in the game. Terran society in general is based on the fascist, militarist future of Starship Troopers. After trying to save the colonists of Mar Sara this happens to Jim Raynor:
(after destroying the Infested Command Center)
Adjutant: Receiving incoming transmission.
Edmund Duke: Marshal Raynor, by destroying a vital Confederate installation, you and your men have violated standing colonial law. As of right now, you're all under arrest. I suggest you throw down your weapons and come peaceably.
Jim Raynor: Are you outta your mind!? If we hadn't burned that damn factory, this entire colony could have been overrun! Maybe if you hadn't taken your sweet time in getting here -
Edmund Duke: Now I asked you nice the first time, boy. I didn't come here to talk with you. Now throw down them weapons!
Jim Raynor: Guess you wouldn't be a Confederate if you weren't a complete pain in the ass.
The Confederacy continues to be greedy, short-sighted and authoritarian throughout the campaign until they are violently brought down. They regularly sacrifice their expendable ground troops and their wars are fought more for internal control than for external domination. This is all too similar to the plot and feel of Starship Troopers.
Another homage is the Ghost. In Starship Troopers psychics form an internal police with their own set of shadowy goals. Indeed, the psychics of Starship Troopers form an important part of the clandestine strategy against “the bugs” in trying to overcome the “brain bug” leaders through psychic powers. Compare the plots:
Sarah Kerrigan: You all know that the Confederates run a program for psychically gifted humans, training them to be Ghosts. Those running the program found that the Zerg are attuned to the psychic emanations of Ghosts.
Jim Raynor: So the Zerg are here for you, darlin'? This keeps gettin' better and better.
Sarah Kerrigan: Shut up. There's been a lot of secret Confederate research surrounding Ghosts and the Zerg. What we stole was a small but critical piece of the puzzle: design for a Transplanar Psionic Waveform Emitter. The emitters broadcast the neural imprint of a Ghost, but at a much greater magnitude. These things reach across worlds.
And to continue the above dialogue:
Arcturus Mengsk: The Confederacy used these Psi Emitters to lure the Zerg into isolated containment areas. Your colony-Mar Sara-Commander, was one such location.
Jim Raynor: What are you saying?
Arcturus Mengsk: I'm saying the Zerg are a secret weapon developed by the Confederacy. I'm saying you were all subjects of a Confederate weapons test.
Just as they destroyed Korhal with nuclear weapons to establish dominance a generation ago, they would use the Zerg to put an end to their rivals. Only this time there'd be no outrage; who could suspect the aliens were their creation? No, they'd be lauded as heroes for coming in and destroying the Zerg. It's time the Confederacy paid for its crimes.
It should be mentioned that the Psi Corps in Babylon 5, a series that have formed core parts of the Protoss identity and which will be covered then, are very similar trope-wise to the ones in Starship Troopers.
This trope of “mankind’s authoritarian rulers create an evil superweapon that turns on themselves” is part and parcel of sci-fi plots. As a sidenote I always thought it was very interesting that the start of the sc1 campaign suggests, like Mengsk states above, that the Zerg are a creation of the Confederacy. This idea is so implanted through use of the trope in the first few missions that I always suspected that it was the original intent of the creators to go for this trope rather than the “two diametrically opposed ancient races representing spiritual and philosophical concepts battle it out for aeons but humans are the best and worst of two worlds and solve it”-trope (which I will write about in the Protoss and Zerg installments).
I hope you enjoyed this part and if I missed something then go ahead and leave a comment!