The Guyver ([a.k.a.: Mutronics] Steve Wang & Screaming Mad George, 1991)

Created by former hentai artist Yoshiki Takaya in 1985, the long-running Guyver manga series ran into the magazine Shonen Captain.  Chronicling the adventures (and misadventures, old friend) of Japanese student Sho Fukamachi after his discovery of the alien Guyver module and his subsequent battles against the faceless and monolithic Chronos Corporation and their hordes of shapeshifting mutant hybrid Zoanoids.  Initially adapted for the moving image as the 55 minute OVA (Original Video Animation - an animated movie or series made with the intention of going direct to home video rather than for cinematic or television transmission) Guyver: Out of Control in 1986, the property was made into a full series of twelve episodes from 1989 to 1992 as The Guyver: Bio-Booster Armour, the guise in which i first encountered it in the early to mid '90s.  Released  in the UK by Manga Entertainment episode by episode (or 'Data' by 'Data', each VHS being dubbed Data 1, Data 2, etc.), with one 30 minute installment - plus Guyver and Zoanoid 'fact files' appended at the end of each - per videocassette (now there's a word that seems positively archaic nowadays.  Videocassette?  How arcane), my adolescent self thrilled to see Sho, the love of his life Mizuki Segawa, her brother (and Sho's best friend) Tetsuro, and their unreliable sometimes ally sometimes enemy Agito Makashima taking on the Chronos Corp to prevent the Zoanoid conquest of the Earth, aided by Sho's merging with the alien Guyver technology to create a secret identity as he becomes encased in the bio-booster armour of the title, becoming a Japanese superhero in the tradition of Spectreman (1971-1972) and Ultraman (originally 1966-67, but ongoing as sporadic series, miniseries and films as recently as 2015).

The directorial debut for special effects creatives Steve Wang and Screaming Mad George (Joji Tani to his mum) - who between them had been responsible for the creature effects in such films as Renny Harlin's A Nightmare on Elm Street 4: The Dream Master (1988), Frederico Prosperi's "man's arm-into-snake's head" curio Curse II: The Bite (1989), Donald G. Jackson and R.J. Kizer's Rowdy Roddy Piper classic Hell Comes to Frogtown (1988) and Joe Dante's postmodern sequel Gremlins 2: The new Batch (1990) - The Guyver (released on VHS in the UK as 'Mutronics') certainly doesn't scrimp on the monster SFX front.  Retaining the vague plot outline of the Manga and anime versions of the story, the movie Americanises the lead character from Sho Fukamachi to the blond-haired Anglo gwai lo 'Sean Barker' (Jack Armstrong), who attends martial arts classes to emulate his action hero idols much to the exasperation of his Aikido instructor and the derision of fellow students such as part-time gangbanger Craig (Johnnie Saiko, whose credits include the intriguingly titles Chicks With Sticks, Part 3).  Sean's obvious intrigue with all things of the Orient include his Japanese girlfriend Mizky Segawa (Vivian Wu - the character's name being inexplicably slightly altered from Mizuki), whose father Dr. Tetsu Segawa had been working for the mysterious Chronos Corporation before his mysterious murder, drawing this Occidental tourist into a web of alien intrigue.

Sean discovers the object that Dr. Segawa had given his life to hide from the clutches of Chronos - the alien Guyver unit, a weaponised suit of armour that bonds with a host to create a symbiotic lifeform with the power to wipe out the hybrid Zoanoid creatures of Chronos.  Accidentally bonding with the Guyver, Sean finds himself the baffled new owner of a pair of vampire-bite style wounds in the back of his neck which pulsate with a life of their own when he is angry or in imminent physical danger before his cry of "GUYVER!" releases his symbiotic star-born sibling from its dormant phase of taking a nap in the nape of his neck.  Wires shoot out from his pinhole pricks and wrap around his body like living tendrils, then these chaotic coaxial cables form and assemble the Guyver suit around him: a blue-green armour plated alien-killing machine complete with elbow-mounted razor-sharp blades and an oxygen mask-style face plate which periodically "breathes" by hissing gas (and, quite possibly, prompting a murmur of "Are you my Mummy?" from viewers.  Or me, at least...).

Also involved in investigating the shapeshifting shenanigans of this mysterious company is FBI agent Max Reed (Star Wars' own Mark Hamill, during his post-Jedi, pre-Joker interregnum), who was working with the late Dr. Segawa to investigate Chronos.  Reed joins Sean / The Guyver to rescue Mizky when she is kidnapped as a hostage by head Zoanoid Oswald Lisker (played with his trademark google-eyed baldness by Michael Berryman of The Hills Have Eyes [Wes Craven, 1977] fame), the killer of Mizky's father who can transform at will into a seven-foot tall befanged and beclawed reptilian nightmare.  In charge of the Corporation's plans to convert humankind into alien hybrids and conquer the Earth (as you do) is the evil Fulton Balcus, played with villainous relish and garnish on the side by the late David Gale (best known to genre fans as the malevolent telepathic head of Dr Carl Hill in Re-Animator [Stuart Gordon, 1985] and its sequel), who walks the captive Mizky down the "Growth Corridor": a passage lined with glass cabinets containing the growing and mutating forms of neophyte Zoanoids in a sequence reminiscent Boris Karloff in Paul Kohner's The Black Cat (1934) - although unlike that film, these crysilline coffins are ocupied not by the embalmed dead but are replete with pulsating, fulminating life.

In what other film, though, can one expect to see Mark Hamill - Luke Skywalker himself! - transforming, Gregor Samsa-style, into a giant cockroach?

Bizarrely, this film - featuring as it does the heroic lead of the Star Wars saga - features some incidental characters who bear characteristics in common with the space saga's inhabitants of the Galaxy Far Far Away.  Jimmie Walker's Striker transmutes into a Zoanoid form replete with piscine fishlike features and flappy webbed ears horrifyingly reminiscent of outer space's most feared, loathed and hated scourge Jar Jar Binks (carrying with him the same questionable and troubling racial stereotypical exaggerations that Lucas failed to see in his creation of eight years later, and likewise being physically performed by a black actor.  Striker manages to push things further though, by busting into the occasional rap, replete with Flava Flav's trademark "Boyyyeeee!!!"  Perhaps had Lucas possessed the visionary acumen with which his followers credit him, we could have had Binks performed in a similar manner?  Wait - WTF am i SAYING?!!?)

Also, Striker's Zoanoid compatriot Ramsey (Peter Spellos) transforms into a mutronic form that is blue-skinned and with a prehensile trunk, rendering him the spitting image of Return of the Jedi songstress Sy Snootles on steroids.

This film may be of dubious canonicity among Guyver fandom, but i think we've firmly established that Star Wars-wise, it's as canon as hell.