The IG-series represented a line of droids that Holowan Laboratories developed and produced during and after the Clone Wars. By the New Republic era, sourcing IG memory circuits became difficult, as their production had ceased. The InterGalactic Banking Clan commanded an army of IG lancer droids, sharing them with the Confederacy of Independent Systems. These droids were ultimately deployed within the Separatist Droid Army, undergoing field tests that proved their effectiveness during the war. This success led to Holowan securing another contract to construct the IG-100 MagnaGuard, serving as elite protectors for high-ranking Separatist officers. Soon after the conclusion of the conflict, Holowan Laboratories, emboldened by the success of their droids, initiated the development of more advanced IG units, notably the IG-RM bodyguard and enforcer droids.
Among these new models was the IG-88 assassin droid, a group of five identical assassin droids that, immediately after activation, slaughtered their creators and fled their laboratories to wander the galaxy. Shortly after their creation, the new IG-series units were declared illegal. Several of these droids subsequently operated as bounty hunters, including the notorious IG-88B.
During the Republic Era of the Galactic Republic, Holowan Laboratories produced IG lancer droids for the InterGalactic Banking Clan's droid army, utilizing plans from Phlut Design Systems's unsuccessful assassin droid project. These droids fought alongside IG-227 Hailfire-class droid tanks under the command of the Muun officer corps. As the Clone Wars began, the Clan's army was incorporated into the larger Army of the Confederacy of Independent Systems, with IG lancer droids serving alongside B1-series battle droids throughout the conflict. The success of the lancer and Hailfire droids resulted in the Laboratories receiving a contract to develop an elite bodyguard droid class for the Separatists' high-ranking officers, including General Grievous.
The resulting IG-100 MagnaGuard served alongside Grievous until the war's end, also escorting the Separatist leadership on their final journey to Mustafar. Another specialized model created by Holowan for the Separatists was the IG-86 sentinel droid, an experimental combat unit designed to be a superior battle droid. They were heavily utilized by the Banking Clan's Collections and Security Division, but were not as widely adopted as the B1s, which remained the Separatists' standard battle droid. However, they were frequently employed by third parties, including bounty hunters such as Cad Bane, and other criminals.
Following the conclusion of the War and the Separatists' defeat, which marked the rise of the Galactic Empire, Holowan Laboratories, encouraged by their wartime achievements, resolved to develop new, more advanced and specialized droid types. One of the first models created was the IG-RM bodyguard and enforcer droid, designed to be as intimidating and frightening as possible. This unit became a common sight among smugglers and criminals, earning them the nickname "thug droids". Holowan's subsequent, and possibly final, attempt at creating a superior battle model was the IG-88 assassin droid, referred to as "Phlutoids" in honor of the inspiration behind Holowan's initial success. These were five identical, highly advanced assassin droids that slaughtered their creators upon activation and destroyed the laboratories where they were housed.
Two of the five droids, IG-88C and IG-88D, went on to operate as bounty hunters throughout the galaxy, while IG-88B independently reprogrammed himself, becoming a renowned bounty hunter of his era and one of the six hunters invited by Sith Lord Darth Vader to locate his son Luke Skywalker's associate, Han Solo. The droid designated IG-88A would later plan to overthrow all organic life.
Chalmun's Cantina in Mos Eisley featured at least one dispenser above the bar crafted from the hollowed-out head of an old IG-series droid.
During the New Republic period, IG memory circuits were out of production and difficult to obtain. Advances in droidsmithing by the Anzellans on Nevarro enabled the modification of an IG unit, IG-11, after it was destroyed. The droid's memory circuit was removed, and its Artificial intelligence was deactivated. Reduced to basic motor functions, the drone—now called IG-12—was used as a mechsuit for the alien Grogu. Later, IG-11 was fully repaired with spare parts and assigned as the marshal of Nevarro.
In addition to their main series, Holowan Laboratories also produced several specialized or unique IG-series assassin droids, including the security droid BK-86, the bounty hunter IG-11, the enforcer IG-70, and the small-time bounty hunter IG-90. IG-11 was also modified into a custom-made mech, IG-12, by Anzellan Droidsmiths and used to carry the Mandalorian foundling Din Grogu.
IG-series droids were humanoid in form, featuring conical heads and claw-like appendages instead of hands. They were designed as class four droids with a focus on combat enhancements, including acid-resistant servo wires, a range of sensors for detecting movement, heat, and sound, and damage-resistant armor. Most of these droids were built for agility, enabling them to engage enemies effectively in close combat. Others, like the IG-RM droids, were slower but possessed greater strength. They remained extremely dangerous even when severely damaged; an IG-11 droid managed to attack and overwhelm a Mandalorian bounty hunter wearing full beskar armor despite lacking legs and an arm and having a severely damaged torso.
To safeguard Holowan's corporate secrets, at least the IG assassin units were programmed to self-destruct using a built-in self-destruct mechanism that even liberated droids could not override (although they could still choose to override the mechanism if escape was possible). Despite its nature, the mechanism would not completely destroy the droid, but would instead irreparably damage its most critical components, such as the droid brain and chassis.