3. The Geonosian Hive Army
An integral species throughout the entirety of the Clone Wars, the Geonosians were no stranger to intense combat. From the First Battle of Geonosis in 22 B.B.Y., to the Second Battle of Geonosis a year later, and the lingering harassment of Republic forces that followed, the Geonosians proved themselves to be remarkably resilient foes to any forces they opposed.
Perhaps best known for their incredible production capabilities, the Geonosians utilized the same ingenuity behind their manufacturing in their battle strategy. Preferring to utilize hit and run tactics in tandem with traditional defenses, Geonosian warriors would lurk in the massive spires that littered their homeworld, swooping down out of the caverns to drag away enemy soldiers one by one as Geonosian defensive emplacements blasted away at the main force of oncoming enemies.
The Geonosian Hive Army had a plethora of highly effective weaponry at their disposal due to the inherent ingenuity of the Geonosians as a species. One of the more popular weapons utilized by the Hive Army was the LR1K sonic cannon. Equipped with a highly advanced targeting computer, this cannon could instantly kill a clone trooper and was a very effective artillery weapon. Archduke Poggle the Lesser rushed these weapons into production after secretly declaring his allegiance to the Confederacy of Independent Systems.
Eventually, the entire Geonosian species, save for one survivor, was wiped out by the Empire following their completion of the first Death Star.