I thought it'd be fun to go through the various monsters and point out cultural references SP has put into the game. Some have been discussed in detail before, but I thought an exhaustive discussion might be interesting. Here are the commons, uncommons, and rares. I'll update the thread with more discussion over time.
Tyrannoking
His description begins with “Hail to the king, baby!” This line was originally spoken by Ash in the classic horror comedy Army of Darkness. It’s also subsequently been used by classic shooter hero, Duke Nukem.
Bloomskips
Bloomskips’ description makes clear that SP wants you to think of the Piranha Plants from Super Mario Bros.: “Bloomskips feel at home when popping out of dark, tight spaces like pipes! Just hope that you aren't a plumber or he's coming for you!”
Heimdal
Heimdall (or Heimdallr) in Norse mythology is a being with foreknowledge, vigilantly keeping watch for Ragnarok. This monster shares little more than a name and Nordic look with him.
Metanephrops
This monster gets its name from metal, obviously, but also the scientific name for the lobster family, Nephropidae.
Djinn
Djinn’s description references the Disney movie, Aladdin, saying that “you’ve never had a friend like him before!”
Bonbon
His description seems to reference the hilarious (and explicit) song, “Tribute” by Tenacious D. In that song, Jack Black sings that “this is not the greatest song in the world, no, this is a just a tribute.” Similarly, Bonbon is not the greatest monster in the world, but is just a tribute.
Koopigg
His name and turtle design are references to Mario’s nemesis, King Koopa (or more often in modern day, Bowser). His description says that he’s King Koopa’s son and that you won’t find him kidnapping princesses.
Rudicius
Rudicius’ name, description, and even appearance seem to reference the ancient wise man, Confucius.
Molem
His description mentions the fall of Helmantica. This is an ancient city now known as Salamanca in Spain. The city itself was captured and occupied by various peoples and groups throughout history. His name is obvious play on the mythical Golem creature of Jewish folklore.
Boneticore
Boneticore’s name and design are inspired by the Persian mythological creature, the manticore (a human’s head, a lion’s body, and a spined or sometimes scorpion tail). Like the Boneticore, whose special attack is called Spike Cloud, the manticore hurled quilled spikes at his enemies.
Metaselach
Given the liquid metal, shapeshifting, his design reminds me of the T-1000 from T2. I don’t know that he’s a direct reference to the time travelling machine from the future or if he’s merely inspired by that sort of design.
Garuda M3
Nothing in Garuda M3’s design seems to reflect his namesake, but Garuda is a mythological bird-like creature most often ridden by the god Vishnu.
Crux
Crux’s special attack is called “Swerda,” a derivation of the Norse “sverd” meaning “sword.”
Dan Felino
If you couldn’t guess, he’s an on the nose reference to Dan Marino, the famous Miami Dolphin quarterback.
Trevor
Trevor is the living embodiment of various Irish references from his design to the names of each of his attacks.
Crushmore
Do I need to explain the references to Mount Rushmore?
LaCroc
Named and designed for the French tennis player René Lacoste, who was nicknamed “The Crocodile.”
Nereida
Nereids were sea nymphs out of Greek mythology.
Cristobal
Like Crushmore, Cristobal is an obvious reference, this time to the fabled explorer, Christopher Columbus.
Hedgy
Released during the Videogames Maze, what other classic hedgehog could this be a reference to other than the super fast, ring collecting Sonic the Hedgehog?
Nanukk
Nanook is a mythological/religious figure of the Inuit people who was connected with polar bears. Nanukk, on the other hand is a sort of walrus but is certainly a creature of the north, from where he is inspired.