These companies produced body kits, spoilers, arches, wings, and skirts in the 70's, 80's, and 90's. Many of their products are very collectable today. Some are still in production, some are not.
Tuning company ABT developed a performance Mk1 Golf in the early 1980's with a widebody kit and front spoiler. I could not find much information on the kit's availability, though Spanish website KitsDeFibra.com seem to sell similar looking parts.
Wheel manufacturer BBS created a series of Mk1 Golf exterior parts, including front and rear spoilers, skirts and arches.
I could find very little about this company, but it seems Alain Lalite was an auto accessories importer from France in the mid-80's. He seems to have been involved in development of a square headlight front end treatment that was popular on BMWs, as well as a similar product for Mk1 Golfs.
Hella
Hella, the automotive lighting company, did manufacture a front and rear spoiler and special grill. As far as I can tell there were marketed under the Hella Sports product line.
Kamei
German company Kamei now make accessories like car roof boxes, but in the 70's and 80's they produced spoilers, lips, and body kits for many cars including Mk1 Golfs. Their kits ar'nt just about style. In the early 1980's they were heavily involved in motor sport, sponsoring many drivers and cars. Mk1 Kamei kits are now quite sort after.
They are well known for producing the X1 kit, featuring re-styled headlights and grill.
Information on Mk1 Golf Orciari body kits is hard to find, with there being more information available on Mk2 kits.
In the 80's Orciari seems to have produced the Kira body kit, which included front and rear spoilers, skirts and wheel arches, and streamlined wing mirrors.
Taifun was a German tuning company who also made a square headlight style front-end treatment for BMWs. They also produced a similar style front end for Mk1 Golfs, though they are hard to find.
In the '90s, a British company called Top Techniks in West Sussex created a multi-piece, foam infused, removable hard-top kit for the Cabriolet called the Vikus. Only 5 were made, one still with the original creator, and one of which was scrapped. Two are probably still in the UK, and the last was shipped to Bermuda making this a very rare accessory indeed. More information here.
Voomeran offer a few different sized wide-body style flared arches, as well as Berg Cup style front spoiler and rear wing.
I found the online store New German Performance has the best range of Voomeran products.
Zender are a composite and product design company who, among other things, create after-market automotive body kits.
In the 80's Zender created the Z-2 and Z-20 body kits, that include a front grill treatment, for the Mk1 Golf
These companies currently manufacture body kits for Mk1 Golfs.
South African company Evo produces the R-Line Inspired kit. As the name suggests, it emulates the rare R-Line Citi Golf's factory installed body kit.
Kerscher produces a body kit (I couldn't find a specific name for it) for both the hatch and cabriolet. It includes front and rear bumpers, and wide body wheel arches with ducted rear air intakes.
Spanish website KitsDeFibra.com sell a number of Group 2 Rally style body accessories.
LEAP, from Mexico, offer a wide body kit called the ONE.
Romanian based tuning company Magna, offer a series of fiberglass kits, bumpers, skirts.
These include the Corrado inspired RX and Vortex wide body kits and grill treatments, the Recto bumper and skirts, and the RS front bumper and lip.
Rieger are a German tuning company. They offer the Corrado inspired GTO kit, as well as front and rear spoilers, lips, and skirts.
Plastics manufacturer Schmidt offer 2 kits for the Mk1: a wide body kit and a Group H style kit. They also manufacture lightweight plastic panels, like fenders and bonnets.
Clipper: this was applied by the factory to Cabriolets from 1987 onwards. It features plastic front and rear bumpers, wheel arches, and side skirts, and was created in an effort to give the aging model a new, modern appearance going into the 90's. It's a common and easy to find kit.
GTi: There is no official GTi "kit", but early GTis received plastic wheel arches extensions and a chin spoiler.
Citi Golf R-Line: there was a factory insalled kit for the South African R-Line. Evo Body kits have their own R-Line "inspired" version.
Though not a body kit, Heritage Parts also sell reproduction 'small' type early chrome bumper kits (they also have a matte black option).
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